Pre-graphitic carbonaceous insertion compounds and use as anodes in rechargeable batteries

ABSTRACT

Carbonaceous insertion compounds and methods for preparation are described wherein the compounds comprise a highly disordered, impurity free, hard pre-graphitic carbonaceous host. Carbonaceous insertion compounds can be prepared which have large reversible capacity for lithium yet low irreversible capacity and voltage hysteresis. Such insertion compounds can be prepared by simple pyrolysis of suitable epoxy, phenolic resin, or carbohydrate precursors at an appropriate temperature. These insertion compounds may be suitable for use as high capacity anodes in lithium ion batteries.

FIELD OF THE INVENTION

[0001] The invention pertains to the field of carbonaceous materialsand, in particular, to pre-graphitic carbonaceous insertion materials.Additionally, the invention pertains to the field of rechargeablebatteries and, in particular, to rechargeable batteries comprisingcarbonaceous anode materials.

BACKGROUND OF THE INVENTION

[0002] The group of pre-graphitic compounds includes carbonaceousmaterials that are generally prepared at low temperatures (eg: less thanabout 2000° C.) from various organic sources and that tend to graphitizewhen annealed at higher temperatures. There are however both hard andsoft pre-graphitic carbon compounds, the former being difficult tographitize substantially even at temperatures of order of 3000° C., andthe latter, on the other hand, being virtually completely graphitizedaround 3000° C.

[0003] The aforementioned set of compounds has been of great interestfor use as anode materials in lithium-ion or rocking chair typebatteries. These batteries represent the state of the art in smallrechargeable power sources for consumer electronics applications. Thesebatteries have the greatest energy density (Wh/L) of conventionalrechargeable systems (ie. NiCd, NiMH, or lead acid batteries).Additionally, lithium ion batteries operate around 3½ volts which isoften sufficiently high such that a single cell can suffice for manyelectronics applications.

[0004] Lithium ion batteries use two different insertion compounds forthe active cathode and anode materials. Insertion compounds are thosethat act as a host solid for the reversible insertion of guest atoms (inthis case, lithium atoms). The structure of the insertion compound hostis not significantly altered by the insertion. In a lithium ion battery,lithium is extracted from the anode material while lithium isconcurrently inserted into the cathode on discharge of the battery. Thereverse processes occur on recharge of the battery. Lithium atoms travelor “rock” from one electrode to the other as ions dissolved in anon-aqueous electrolyte with the associated electrons travelling in thecircuit external to the battery.

[0005] The two electrode materials for lithium ion batteries are chosensuch that the chemical potential of the inserted lithium within eachmaterial differs by about 3 to 4 electron volts thus leading to a 3 to 4volt battery. It is also important to select insertion compounds thatreversibly insert lithium over a wide stoichiometry range thus leadingto a high capacity battery.

[0006] A 3.6 V lithium ion battery based on a LiCoO₂/pre-graphiticcarbon electrochemistry is commercially available (produced by SonyEnergy Tec.) wherein the carbonaceous anode can reversibly insert about0.65 Li per six carbon atoms. (The pre-graphitic carbon employed is adisordered form of carbon which appears to be similar to coke.) However,the reversible capacity of lithium ion battery anodes can be increasedby using a variety of alternatives mentioned in the literature. Forexample, the crystal structure of the carbonaceous material affects itsability to reversibly insert lithium (as described in J. R. Dahn et al.,“Lithium Batteries, New Materials and New Perspectives”, edited by G.Pistoia, Elsevier North-Holland, p1-47, (1993)). Graphite for instancecan reversibly incorporate one lithium per six carbon atoms whichcorresponds electrochemically to 372 mAh/g. This electrochemicalcapacity per unit weight of material is denoted as the specific capacityfor that material. Graphitized carbons and/or graphite itself can beemployed under certain conditions (as for example in the presentation byMatsushita, 6th International Lithium Battery Conference, Muenster,Germany, May 13, 1992, or in U.S. Pat. No. 5,130,211).

[0007] Other alternatives for increasing the specific capacity ofcarbonaceous anode materials have included the addition of otherelements to the carbonaceous compound. For example, Canadian PatentApplication Serial No. 2,098,248, Jeffrey R. Dahn et al., ‘ElectronAcceptor Substituted Carbons for Use as Anodes in Rechargeable LithiumBatteries’, filed Jun. 11, 1993, discloses a means for enhancing anodecapacity by substituting electron acceptors (such as boron, aluminum,and the like) for carbon atoms in the structure of the carbonaceouscompound. Therein, reversible specific capacities as high as 440 mAh/gwere obtained with boron substituted carbons. Canadian PatentApplication Serial No. 2,122,770, Alfred M. Wilson et al., ‘CarbonaceousCompounds and Use as Anodes in Rechargeable Batteries’, filed May 3,1994, discloses pre-graphitic carbonaceous insertion compoundscomprising nanodispersed silicon atoms wherein specific capacities of550 mAh/g were obtained. Similarly, specific capacities of about 600mAh/g could be obtained by pyrolyzing siloxane precursors to makepre-graphitic carbonaceous compounds containing silicon as disclosed inCanadian Patent Application Serial No. 2,127,621, Alfred M. Wilson etal., ‘Carbonaceous Insertion Compounds and Use as Anodes in RechargeableBatteries’, filed Jul. 8, 1994.

[0008] Recently, practitioners in the art have prepared carbonaceousmaterials with very high reversible capacity by pyrolysis of suitablestarting materials. At the Seventh International Meeting on LithiumBatteries, Extended Abstracts Page 212, Boston, Mass. (1994), A. Mabuchiet al. have demonstrated that pyrolyzed coal tar pitch can havereversible specific capacities as high as 750 mAh/g at pyrolysistemperatures about 700° C. K. Sato et al. in Science 264, 556, (1994)disclosed a similar carbonaceous material prepared by heatingpolyparaphenylene at 700° C. which has a reversible capacity of 680mAh/g. S. Yata et al., Synthetic Metals 62, 153 (1994) also disclose asimilar material made in a similar way. These values are much greaterthan that of pure graphite. The aforementioned materials can have a verylarge irreversible capacity as evidenced by first discharge capacitiesthat can exceed 1000 mAh/g. Additionally, the voltage versus lithium ofall the aforementioned materials has a significant hysteresis (ie. about1 volt) between discharge and charge (or between insertion andextraction of lithium). In a lithium ion battery using such a materialas an anode, this would result in a similar significant hysteresis inbattery voltage between discharge and charge with a resultingundesirable energy inefficiency.

[0009] It is not understood why the aforementioned carbonaceousmaterials have very high specific capacity. (However, J. Dahn et al.,Electrochimica Acta, Vol. 3, No.9, p. 1179-1191, 1993 speculated on thepossibility of certain unorganized carbons exceeding the capacity ofgraphite via lithium adsorption on single graphite layers containedwithin. Also, in the aforementioned reference by K. Sato et al., Lidimer formation was proposed as an explanation for the very highspecific capacity of their carbonaceous material.) All these materialswere prepared at temperatures of about 700° C. and are crystallineenough to exhibit x-ray patterns from which the parameters d₀₀₂, L_(c),a, and L_(a) can be determined. (The definition and determination ofthese parameters can be found in K. Kinoshita, “Carbon—Electrochemicaland Physicochemical Properties”, John Wiley & Sons 1988.) Also, all havesubstantial amounts of incorporated hydrogen as evidenced by H/C atomicratios that are greater than 0.1, and often near 0.2. Finally, itappears that pyrolyzing at higher temperature degrades the specificcapacity substantially with a concurrent reduction in the hydrogencontent. (In the aforementioned reference by Mabuchi et al., pyrolyzingthe pitch above about 800° C. results in a specific capacity decrease tounder 450 mAh/g with a large reduction in H/C. Similar results werefound in the aforementioned reference by Yata et al.)

[0010] The prior art also discloses carbonaceous compounds with specificcapacities higher than that of pure graphite made from precursors thatform hard carbons on pyrolysis. However, the very high specificcapacities of the aforementioned materials pyrolyzed at about 700° C.were apparently not attained. A. Omaru et al, Paper #25, ExtendedAbstracts of Battery Division, p34, Meeting of the ElectrochemicalSociety, Toronto, Canada (1992), disclose the preparation of a hardcarbonaceous compound containing phosphorus with a specific capacity ofabout 450 mAh/g by pyrolyzing polyfurfuryl alcohol. The polyfurfurylalcohol in turn had been prepared from the monomer polymerized in thepresence of phosphoric acid. In Japanese Patent Application Laid Opennumber 06-132031, Mitsubishi Gas Chemical disclose a hard carbonaceouscompound comprising 2.4% sulfur with a specific capacity of about 500mAh/g. These hard carbonaceous compounds have additional elementsincorporated therein and have all been pyrolyzed at sufficienttemperature such that they contain little hydrogen (ie. the H/C atomicratio is substantially less than 0.1). These hard carbonaceous compoundsneither exhibited the very high specific capacities nor the same serioushysteresis in voltage of the aforementioned materials pyrolyzed at about700° C.

[0011] Additionally, other high capacity carbonaceous materials haverecently been prepared which show high capacity for lithium and littleor no voltage hysteresis. In Paper 2B05 at the 35th Battery Symposium inNagoya, Japan, Nov. 14-16, 1994, Y. Takahashi et al. describe materialswith reversible capacities of about 480 mAh/g, but do not give thedetails of their preparation. In paper 2B09 at the same Symposium, N.Sonobe et al. describe hard carbon materials made from petroleum pitchwith reversible capacities near 500 mAh/g. The synthesis proceduretherein was not given.

[0012] Japanese patent application laid open number 06-089721 discussesthe high capacity advantages of hard disordered carbons in terms of theparameters P_(s) (the fraction of stacked carbon), n_(ave) (the numberof graphene sheets per stack), and SI (the stacking index). Therein, SIis defined by the height of the {002} peak relative to the localbackground. Therein, carbonaceous compounds having values of SI below0.76 were claimed and the examples provided had a minimum SI of 0.67.Reversible capacities for lithium up to 460 mAh/g were obtained.However, voltage curves (and hence hysteresis characteristics) andirreversible capacities were not reported. Additionally, discussion anddata regarding hydrogen contents after pyrolysis and surface areaaccessible to non-aqueous electrolyte were not provided.

SUMMARY OF THE INVENTION

[0013] This invention comprises novel carbonaceous insertion compoundswith a high reversible capacity for alkali metal insertion, methods ofpreparing said insertion compounds, and the use of said insertioncompounds as electrode materials in electrochemical devices in general.The alkali metal can be lithium and, in such a case, the insertioncompound can have a low irreversible capacity and a small voltagehysteresis between insertion and extraction.

[0014] Carbonaceous insertion compounds of the invention comprise apre-graphitic carbonaceous host and atoms of an alkali metal insertedtherein. The alkali metal inserted can be lithium as would be the casefor use in lithium ion batteries. The empirical parameter R, asdetermined from an x-ray diffraction pattern of the host and defined asthe {002} peak height divided by the background level, is less thanabout 2.2. To achieve a large stoichiometry range for reversibleinsertion of alkali metal, R is preferably less than about 2, and mostpreferably less than about 1.5. The H/C atomic ratio of the host is lessthan about 0.1. The pre-graphitic host has a surface area accessible tonon-aqueous electrolyte that is sufficiently small such that theirreversible capacity is less than about a half that of the reversiblecapacity, and preferably less than about a third that of the reversiblecapacity. The non-aqueous electrolyte can be a solution comprisingethylene carbonate and diethyl carbonate.

[0015] Electrochemical methods are preferably used to determinereversible and irreversible capacities after which an accessible surfacearea can be deduced. However, other physical characteristics can be usedto estimate the accessible surface area. For example, methylene blueabsorption capacity and BET (a standard nitrogen adsorption test)surface area provide such estimates. When the methylene blue absorptioncapacity of the carbonaceous host is less than about 4 micromoles pergram of host or when the surface area of the carbonaceous host asdetermined by BET is less than about 300 m²/gram, the accessible surfacearea can be sufficiently small to meet the capacity requirements.

[0016] Suitable carbonaceous hosts can be rendered unsuitable byrelatively mild oxidation without overly dramatic effects on methyleneblue absorption. On the other hand, the BET surface area may increasesubstantially but still be in a range considered acceptable inprinciple. It has been found that a mildly oxidized carbonaceous hostcan comprise enough surface oxygen such that more than 5% by weight islost after pyrolyzing at about 1000° C. under inert gas. Thus, suitablecarbonaceous hosts preferably have not been oxidized after preparation.Suitable carbonaceous hosts typically lose less than about 5% by weightunder such inert pyrolysis conditions.

[0017] The pre-graphitic carbonaceous host can generally be prepared bypyrolyzing an epoxy precursor, phenolic resin precursor, carbohydrateprecursor or a carbohydrate containing precursor at a temperature aboveabout 700° C., thereby predominantly removing hydrogen from theprecursor. However, the pyrolysis temperature cannot be too high inorder that the empirical parameter R, determined from an x-raydiffraction pattern of the host and defined as the {002} peak heightdivided by the background level, remains less than about 2.2. Alkalimetal atoms can be inserted into the host thereafter by conventionalchemical or electrochemical means to make insertion compounds of theinvention.

[0018] If an epoxy precursor is used, the epoxy precursor can be anepoxy novolac resin and can comprise a hardener in a range from zero toabout 40% by weight. The hardener can be phthallic anhydride and theepoxy can be cured at about 120° C. before pyrolysis. The maximumpyrolysis temperature can be attained by ramping at from about 1° C./minto about 20° C./min. A possible embodiment of the invention can beprepared by pyrolyzing an epoxy novolac resin having the formula

[0019] at a maximum temperature below about 1100° C.

[0020] Alternatively, the epoxy precursor can be a bisphenol A epoxyresin. The maximum pyrolysis temperature can be attained by ramping atabout 30° C./min. A possible embodiment of the invention can be preparedby pyrolyzing a bisphenol A epoxy resin having the formula

[0021] at a temperature about 800° C.

[0022] If a phenolic resin precursor is used, the pyrolysis temperaturecan preferably be above about 800° C. and the empirical parameter R ispreferably less than about 1.6 in order to achieve a large stoichiometryrange for reversible insertion of alkali metal.

[0023] The phenolic resin precursor can be of the novolac or the resoletype. The latter can be preferably pyrolyzed at a temperature in therange from about 900° C. to about 1100° C. Both types can be cured atabout 150° C. before pyrolysis. The pyrolysis temperature for both typescan be maintained for about one hour.

[0024] If a carbohydrate precursor or carbohydrate containing precursoris used, the pyrolysis temperature can be preferably above about 800° C.and the empirical parameter R is preferably less than about 2. Alongwith other previously mentioned advantages, such hosts can haverelatively large tap density, often exceeding 0.7 g/ml.

[0025] Such a carbohydrate precursor or carbohydrate containingprecursor can be selected from the group consisting of sugar, starch,and cellulose or substances containing these materials. Specifically,the carbohydrate precursor can be sucrose, starch, or the cellulose inred oak, maple, walnut shell, filbert shell, almond shell, cotton orstraw.

[0026] The pyrolysis can be performed at a temperature in the range fromabout 900° C. to about 1100° C. for about an hour. It can beadvantageous to attain the pyrolysis temperature quickly, for example byramping at a rate of about 25° C. per minute.

[0027] It can be advantageous to precarbonize the carbohydrate bywashing with an acid (such as concentrated sulfuric acid) beforepyrolysis.

[0028] Compounds of the invention can be used as a portion of anelectrode in various electrochemical devices based on insertionmaterials (eg. supercapacitors, electrochromic devices, etc.). Apreferred application for these compounds is use thereof as an electrodematerial in a battery, in particular a non-aqueous lithium ion batterycomprising a lithium insertion compound cathode; a non-aqueouselectrolyte comprising a lithium salt dissolved in a mixture ofnon-aqueous solvents; and an anode comprising the carbonaceous insertioncompound of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 shows the definition of R on an almost featureless x-raydiffraction pattern of a pre-graphitic carbon in the region around the{002} peak.

[0030]FIG. 2 shows a cross-sectional view of a conventional lithium ionspiral-wound type battery.

[0031]FIG. 3 depicts an exploded view of the laboratory coin cellbattery used in the Examples.

[0032]FIG. 4 shows the H/C atomic ratio versus pyrolysis temperature forthe samples of Prior Art Example 2 and of Epoxy Example 1.

[0033]FIG. 5 shows the x-ray diffraction patterns in the vicinity of the{002} peak for some of the samples of Prior Art Example 2. The patternshave been offset vertically by 2000 counts for clarity.

[0034]FIGS. 6a and 6 b show the voltage versus capacity plots for someof the batteries of Prior Art Example 2.

[0035]FIG. 6a is an expanded version of FIG. 6b in the region near zerovolts. The points at which lithium plating and stripping occur areindicated by arrows for the battery comprising the 550° C. pyrolyzedsample. The plots in each Figure are offset sequentially by 0.05 voltsand 0.1 volts respectively for clarity.

[0036]FIG. 7 shows the x-ray diffraction patterns in the vicinity of the{002} peak for the M20E activated carbon samples of the IllustrativeExample re activated carbons.

[0037]FIG. 8 shows the second cycle voltage versus capacity plot for thebattery containing M30 activated carbon pyrolyzed at 1000° C. of theIllustrative Example re activated carbons.

[0038]FIG. 9 shows the first cycle voltage versus capacity plot for thebattery containing M30 activated carbon pyrolyzed at 1000° C. of theIllustrative Example re activated carbons.

[0039]FIG. 10 compares the second cycle voltage versus capacity plots ofsample no. I of Epoxy Example 1 to that of the 700° C. pyrolyzed sampleof Prior Art Example 2.

[0040]FIG. 11 shows the x-ray diffraction patterns in the vicinity ofthe {002} peak for samples I, II, and III of Epoxy Example 1. Thepatterns have been offset vertically by 1600 counts for clarity.

[0041]FIGS. 12a and 12 b show the voltage versus capacity plots ofsamples I, II, III, and IV of Epoxy Example 1. FIG. 12a is an expandedversion of FIG. 12b in the region near zero volts. The points at whichlithium plating and stripping occur are indicated by arrows for thebattery comprising sample IV. The plots in each Figure are offsetsequentially by 0.05 volts and 0.1 volts respectively for clarity.

[0042]FIGS. 13a and 13 b show the voltage versus capacity plots ofsamples V, VI, VII, and IX of Epoxy Example 1 and illustrates therelation between R and specific capacity for samples pyrolyzed at 1000°C. to 1100° C. FIG. 13a is an expanded version of FIG. 13b in the regionnear zero volts. The points at which lithium plating and stripping occurare indicated by arrows for the battery comprising sample VII. The plotsin each Figure are offset sequentially by 0.05 volts and 0.1 voltsrespectively for clarity.

[0043]FIG. 14 shows the x-ray diffraction pattern in the vicinity of the{002} peak for the samples of FIGS. 13a and b. The patterns have beenoffset vertically by 3000 counts for clarity.

[0044]FIG. 15 shows a summary plot of specific capacity versus R forsample nos. III to IX inclusive of Epoxy Example 1.

[0045]FIG. 16 shows the voltage versus capacity plot of the firstdischarge and charge of the battery comprising sample no. VII of EpoxyExample 1.

[0046]FIGS. 17a and 17 b show the voltage versus capacity plots of abattery of Epoxy Example 2. FIG. 17a is an expanded version of FIG. 17bin the region near zero volts.

[0047]FIGS. 18a and 18 b show the voltage versus capacity plots for thefirst and second cycles respectively for batteries comprising samplesprepared from the A type precursor in Phenolic Resin Example 1. Thecurves have been offset sequentially for clarity. (In both Figures, theshifts are 0.0, 0.15, 0.3, 0.45, and 0.7 volts for sample A700, A800,A900, A1000, and A1100 respectively.)

[0048]FIGS. 19a and 19 b show the voltage versus capacity plots for thefirst and second cycles respectively for batteries comprising samplesprepared from the B type precursor in Phenolic Resin Example 1. Thecurves have been offset sequentially for clarity. (In FIG. 19a, theshifts are 0.0, 0.1, 0.25, 0.3, and 0.4 volts for sample B700, B800,B900, B1000, and B1100 respectively. In FIG. 19b, the shifts are 0.0,0.1, 0.3, 0.5, and 0.8 volts for sample B700, B800, B900, B1000, andB1100 respectively).

[0049]FIGS. 20a and 20 b show the voltage versus capacity plots for thefirst and second cycles respectively for batteries comprising samplesprepared from the C type precursor in Phenolic Resin Example 1. Thecurves have been offset sequentially for clarity. (In both Figures, theshifts are 0.0, 0.15, 0.3, and 0.45 volts for sample C800, C900, C1000,and C1100 respectively.)

[0050]FIG. 21 shows the capacity versus cycle number for the batterycomprising sample B1000 of Phenolic Resin Example 1.

[0051]FIG. 22 shows the voltage versus capacity plots for the secondcycle of batteries comprising samples prepared from the B type precursorin Phenolic Resin Example 2. The plots have been sequentially offset by0.1V for clarity.

[0052]FIG. 23 shows the powder x-ray diffraction profiles for thedirectly pyrolyzed sucrose samples (numbers 1, 2, 4, 5, 6, and 7) of thecarbohydrate and carbohydrate containing precursors examples. The datapresented has been offset sequentially by 500 counts for clarity.

[0053]FIG. 24 shows the powder x-ray diffraction profiles for samplespyrolyzed at 1000° C. from starch and cellulose precursors (numbers 14,15, 16, 17, and 18). The data have been offset sequentially by 500counts for clarity.

[0054]FIGS. 25a and b show the voltage versus capacity plots for thesecond cycle for representative batteries comprising sample numbers 8,2, 10, 11, and 12 pyrolyzed between 700° C. and 1100° C. FIG. 25a is amagnified view of a portion of FIG. 25b. The onset of lithium platingduring discharge and the termination of lithium stripping during chargeis indicated by the vertical lines for sample 8 in FIG. 25a. The datahas been offset sequentially for clarity by 0.05V in FIG. 5a and by 0.1Vin 25 b.

[0055]FIGS. 26a and b show the voltage versus capacity plots for thesecond cycle for representative batteries comprising sample numbers 2,18, 14, 16, and 15 pyrolyzed at 1000° C. FIG. 26a is a magnified view ofa portion of FIG. 26b. The data has been offset sequentially for clarityby 0.05V in FIG. 26a and by 0.1V in 26 b.

[0056]FIG. 27 shows the capacity versus cycle number for the twobatteries containing electrodes made from sample number 8.

[0057]FIG. 28 shows the capacity versus cycle number for one of the twobatteries containing electrodes made from sample number 14.

[0058]FIG. 29 shows the capacity versus cycle number for the twobatteries containing electrodes made from sample number 18.

[0059]FIG. 30 compares the voltage profiles of cycles 5 and 6 of thebatteries comprising carbohydrate precursor sample number 8 and phenolicresole resin precursor sample B1000.

[0060]FIG. 31 shows the differential capacity versus voltage during 5thcycle charging of the two batteries of FIG. 30.

[0061]FIG. 32 shows the x-ray diffraction patterns of several oxidizedsamples from the Illustrative Examples re burnoff.

[0062]FIGS. 33a (magnified view) and b show the voltage versus capacityplots for the second cycle of representative batteries from theIllustrative Examples re burnoff.

[0063]FIGS. 34a and b show plots of the intensity versus scatteringangle and in (intensity) versus q² respectively for the samples from theIllustrative Examples re small angle scattering.

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS OF THE INVENTION

[0064] Insertion compounds of the invention comprise hard pre-graphiticcarbonaceous hosts having very poorly stacked graphene layers, littlehydrogen content, and a small surface area accessible to commonnon-aqueous electrolyte solutions.

[0065] The carbonaceous hosts of said compounds can be derived frompyrolysis products of suitable precursors. Suitable precursors are thosethat can be pyrolyzed such that little hydrogen remains (ie. such thatthe H/C atomic ratio is less than about 0.1) and yet such that the hostdoes not graphitize to such an extent that the empirical parameter R asdetermined by x-ray diffraction pattern exceeds about 2.2.

[0066] Herein, the empirical parameter R is used for purposes ofdescribing such disorganized structures and is determined by dividingthe {002} peak height by an estimate of the background level at theBragg angle corresponding to the position of the {002} peak. R providesa convenient empirical means of quantifying the degree of graphitizationof these compounds which have almost featureless x-ray diffractionpatterns. FIGS. 1 illustrates the definition of R on a representative,almost featureless x-ray diffraction pattern of a pre-graphitic carbonin the region around the {002} peak. A tangential line is drawn below,but in the immediate vicinity of, the {002} peak to exclude thebackground. The point where a parallel line just intersects the peakdefines the position of the maximum peak height. The value B in FIG. 1thus indicates the {002} peak height and the value A indicates thebackground estimate. R can thus be used to distinguish the stackingorder in very disorganized materials. To quantitatively measure Rreproducibly, all of the x-ray beam of the diffractometer must beconfined to the carbon sample in the angular range of interest (ie. from10° to 35° when a copper target x-ray tube is used).

[0067] R is related to the aforementioned parameter SI of the prior art.When the local background is relatively flat and/or if the {002} peak isrelatively large compared to the background, SI is approximately equalto 1−(1/R). The prior art claimed SI values below 0.76 and showedcarbonaceous examples having a minimum SI value of 0.67. Using theapproximate conversion formula, these values correspond to R of 4.2 and3.0 respectively.

[0068] This type of insertion compound can have a high reversiblecapacity for alkali metal insertion. When the alkali metal is lithium,the insertion compounds additionally can have a low irreversiblecapacity and a small voltage hysteresis between insertion andextraction. It appears necessary for the carbonaceous host to have asmall surface area accessible to common non-aqueous electrolytesolutions in order to obtain these additional advantages. This isespecially important for application in lithium ion batteries.Electrolyte reactions that consume lithium occur at the anode surface insuch batteries. Thus, use of an anode having a large surface areaaccessible to electrolyte results in substantial irreversible capacityloss and electrolyte loss. These losses are avoided if the anode surfaceis not accessible to the electrolyte. The surface area of thecarbonaceous hosts accessible to common non-aqueous electrolytes is notdirectly measurable though. However, it can be inferred to a certainextent by the observed irreversible capacity of the lithium-carboninsertion compound. Desirably, the accessible surface area is such thatthe irreversible capacity is less than about half that of the reversiblecapacity for practical application in lithium ion batteries. Preferably,the irreversible capacity is smaller still, being less than about athird that of the reversible capacity.

[0069] A method for estimating the accessible surface area can beemployed that is based on the absorption of methylene blue (commonlyused for activated carbons). In the literature (see for example, ActiveCarbon by H. Jankowska, A. Swiatkowski, Jr. Choma, translated by T. J.Kemp, published by Ellis Horwood, New York, 1991), methylene blue (MB)is considered to have an equivalent minimum linear dimension of 1.5 nm.That is, MB is expected to penetrate into pores having diameters greaterthan 1.5 nm. Although non-aqueous electrolyte solutions can haveequivalent linear dimensions smaller than this, generally those ofinterest for commercial applications might be of that order in size.Thus, it was estimated that if certain areas of a sample were notaccessible to MB, then these same areas would also not be accessible toelectrolyte.

[0070] The electrolyte-accessible surface area was often sufficientlysmall if the methylene blue absorption capacity of the carbonaceous hostwas found to be less than about 4 micromoles per gram of host. However,compounds have been synthesized that meet the methylene blue criterionyet still appear to have unacceptably large electrolyte-accessiblesurface area. This is demonstrated in the Illustrative examples tofollow.

[0071] The BET method is a conventional way of measuring surface areaaccessible to nitrogen. This too provides a means of estimating theelectrolyte-accessible surface area of the carbonaceous host. Theelectrolyte-accessible surface area can be sufficiently small whencorresponding BET surface area values are as high as about 300 m²/gramof host. However, hosts might conceivably have larger BET surface areasand still have sufficiently small electrolyte-accessible surface area.

[0072] It has been discovered that carbonaceous hosts of the inventionwhich have been slightly oxidized can have significantly increasedelectrolyte-accessible surface area without exceeding or significantlyexceeding the aforementioned methylene blue absorption or the BETcriteria. Thus, oxidizing represents a means of ruining otherwisesuitable carbonaceous hosts. Also, oxidizing represents a means for finetuning the characteristics of the hosts such that theelectrolyte-accessible surface area of the host cannot be adequatelydistinguished by the aforementioned methods of estimating. Suchoxidation results in the formation of surface oxides which can besubsequently removed by pyrolyzing at high temperature (eg. 1000° C.)under inert gas. Under these circumstances, a weight loss of 5% or morecan be indicative of a host ruined by oxidation. Conversely, a weightloss of less than about 5% after oxidation can be indicative of asuitable carbonaceous host. This is demonstrated in the Illustrativeexamples to follow.

[0073] As is known to those skilled in the art, the capacity values oflithium carbonaceous insertion compounds can vary depending on thechoice of non-aqueous electrolyte employed. Certain choices might alwaysresult in large irreversible capacity values. A solvent mixture known inthe art to be associated with low irreversible capacities comprisesethylene carbonate and diethyl carbonate. Electrolytes based on thissolvent mixture can be suitable for evaluating theelectrolyte-accessible surface area.

[0074] Various precursors can be pyrolyzed to provide the aforementionedtype of carbonaceous hosts that have a high reversible capacity foralkali metal insertion. Certain epoxies, phenolic resins, carbohydratesand/or carbohydrate containing compounds have all been found to besuitable precursors. Suitable precursors include those that, whenpyrolyzed at temperatures above about 700° C., do not graphitize to suchan extent that the empirical parameter R as determined by x-raydiffraction pattern exceeds about 2.2.

[0075] Herein, the term epoxy refers to that group of thermosettingresins based on the reactivity of the epoxide group (as per thedefinition in The Condensed Chemical Dictionary, Ninth Ed., Van NostrandReinhold, 1977). Common members of this group include bisphenol A-basedepoxies and epoxy novolac resins. These are particularly suitableepoxies that, when pyrolyzed above 700° C., provide pre-graphiticcarbonaceous hosts that do not exhibit severe hysteresis in voltage uponinsertion or extraction of lithium. When pyrolyzed at temperatures suchthat R is below 2.2, these hosts exhibit very high specific capacitiesfor lithium. The specific capacity for lithium increases as R decreases.Thus, smaller values of R appear preferable in general. This isillustrated in the epoxy precursor examples to follow wherein R appearsto be preferably less than about 2 and most preferably less than about1.5.

[0076] Phenolic resins can also be suitable precursors and can offersome advantages over epoxies in this application. The pyrolysis of epoxynovolac resins (eg. DEN 438, trademark of DOW) gives product yields near30%. It is well known however that phenolic resins (orphenol-formaldehyde resins) can also be pyrolysed to give hard carbonswith high yield (as for example mentioned in E. Fitzer et al., Carbon 7,643 (1969). Since the former can cost about $5 per pound versus about$1.00 per pound for the latter at the time of this writing, a costadvantage might be expected for phenolic resin precursors.

[0077] Suitable phenolic resin precursors include those of the novolacor resole type. Based on the phenolic resin precursor examples tofollow, it appears preferable to pyrolyze these precursors attemperatures above about 800° C. in order to provide pre-graphiticcarbonaceous hosts that do not exhibit severe hysteresis in voltage uponinsertion or extraction of lithium and that are are also characterizedby low H/C atomic ratios. Smaller values of R appear preferable asillustrated in these examples wherein R appears to be preferably lessthan about 1.6.

[0078] The McGraw-Hill Dictionary of Scientific and Technical Terms,McGraw-Hill, Inc., New York, defines a carbohydrate as any of the groupof organic compounds composed of carbon, hydrogen, and oxygen, includingsugars, starches and celluloses. The carbohydrate precursors of thesubject invention encompass all carbohydrates composed of carbon,hydrogen and oxygen.

[0079] The sugars can comprise monosaccharides (simple sugars),disaccharides (more complex sugars including sucrose, the common tablesugar), and polysaccharides, the latter comprising the entire starch andcellulose families. Starch is a polymer of α-D-glucose while celluloseis a polymer of β-D-glucose. The glucose rings in cellulose have adifferent relative orientation than in starch. Isomers or compounds withsuch orientation differences can behave radically differently inbiochemical processes. However, in inorganic processes, such differencesmay not matter. For example, the physical characteristics andelectrochemical behaviour of insertion compounds prepared by pyrolyzingdifferent isomers would likely be the same.

[0080] The use of carbohydrates as a precursor offers certain advantagesover epoxy and/or phenolic resin precursor options. While phenolicresins can be relatively inexpensive compared to epoxies and can givehigher yields when pyrolyzed (near 60%), the pyrolysis process generatessubstantial amounts of tarry residue which is difficult to dispose ofand may be carcinogenic.

[0081] Naturally occurring carbohydrates are attractive precursorsbecause they are plentiful and relatively inexpensive. For example, oak(predominantly consisting of cellulose) can cost about $0.08 per pound.Even with a pyrolysis yield of 20%, this can result in a cost for theproduct that is about 5 times less than the corresponding cost forphenolic resin derived product. Additionally, carbohydrate precursorscan lead to product with a high tap density which is needed for highvolumetric energy density in lithium ion batteries. Finally,carbohydrate precursors can result in less tarry residue per gram ofcarbon produced than do phenolic resin precursors.

[0082] We have discovered that pyrolyzing suitable carbohydrateprecursors, and carbohydrate containing precursors, above 800° C. canprovide pre-graphitic carbonaceous hosts which have low H/C atomicratios (<0.1). Additionally, pyrolyzing at temperatures such that R isbelow 2.2 provides for hosts with very high specific capacities forlithium. The specific capacity for lithium increases as R decreases. Asshown in the carbohydrate precursor examples to follow, pyrolysisproducts can be prepared with R values less than about 2 that have largereversible capacities. These products also have methylene blueabsorption values less than 4 micromoles per gram and BET values lessthan 300 m²/gram and do not exhibit large irreversible capacities norsevere hysteresis in voltage upon insertion or extraction of lithium.Tap densities as high as 0.7 g/ml can also be achieved.

[0083] Regardless of precursor(s) employed, the pyrolysis should beperformed under a controlled atmosphere to prevent formation ofundesired oxides of carbon. A suitable reaction system could consist ofa reaction tube (quartz for example) installed in a conventional tubefurnace wherein the tube has sealed inlet and outlet connections forpurposes of controlling the atmosphere therein. The precursor(s) couldthus be pyrolyzed in the reaction tube under an inert gas flow or evenunder reduced or elevated pressure.

[0084] The electrolyte-accessible surface area of the pyrolyzed productshould be relatively small. In general therefore, it is undesirable tooxidize the precursor during pyrolysis as this would be expected toresult in an increase in this area. Since the by-product gases ofpyrolysis include unwanted oxidizing gases, it is desirable to removethese quickly.

[0085] Ramping the furnace temperature relatively quickly to thepyrolysis temperature and minimizing the pyrolysis period can also begenerally desirable in order to minimize graphitization of the product.In the case of epoxy or phenolic resin precursor(s), to ensure goodproduct yields, both should ideally substantially pyrolyze rather thansimply evaporate. This issue must be considered in the selection ofpreferred precursor(s). It can therefore be advantageous to cure, orcross-link, the precursor before pyrolysis. The extent of such curingmay be a significant variable affecting the desired ultimate propertiesof the pyrolyzed precursor(s). It may therefore be advantageous toconsider incorporating soaking periods at several temperatures as partof the heat treatment. For example, a low temperature soak might be usedfor curing the precursor(s) prior to a final heating to the pyrolysistemperature. Alternately, the heating rate might be varied to controlthe extent of the curing prior to pyrolysis.

[0086] In the case of carbohydrate precursors, it can be advantageous toprecarbonize the carbohydrate prior to pyrolysis at a low temperature. Ameans for so doing is to wash the carbohydrate with a strong acid whichis subsequently rinsed away.

[0087] The aforementioned product has no alkali metal inserted asprepared. Alkali metal atoms, in particular Li, can be insertedthereafter via conventional chemical or electrochemical means (such asin a lithium or lithium ion battery).

[0088] Generally, powdered forms of such compounds are used in electrodeapplications and thus a grinding of the pyrolyzed product is usuallyrequired. A variety of embodiments, in particular various batteryconfigurations, are possible using electrode material prepared by themethod of the invention. Miniature laboratory batteries employing alithium metal anode are described in the examples to follow. However, apreferred construction for a lithium ion type product is that depictedfor a conventional spiral-wound type battery in the cross-sectional viewof FIG. 2. A jelly roll 4 is created by spirally winding a cathode foil1, an anode foil 2, and two microporous polyolefin sheets 3 that act asseparators.

[0089] Cathode foils are prepared by applying a mixture of a suitablepowdered (about 10 micron size typically) cathode material, such as alithiated transition metal oxide, possibly other powdered cathodematerial if desired, a binder, and a conductive dilutant onto a thinaluminum foil. Typically, the application method first involvesdissolving the binder in a suitable liquid carrier. Then, a slurry isprepared using this solution plus the other powdered solid components.The slurry is then coated uniformly onto the substrate foil. Afterwards,the carrier solvent is evaporated away. Often, both sides of thealuminum foil substrate are coated in this manner and subsequently thecathode toil is calendered.

[0090] Anode foils are prepared in a like manner except that a powdered(also typically about 10 micron size) carbonaceous insertion compound ofthe invention is used instead of the cathode material and thin copperfoil is usually used instead of aluminum. Anode foils are typicallyslightly wider than the cathode foils in order to ensure that anode foilis always opposite cathode foil.

[0091] The jelly roll 4 is inserted into a conventional battery can 10.A header 11 and gasket 12 are used to seal the battery 15. The headermay include safety devices if desired. A combination safety vent andpressure operated disconnect device may be employed. FIG. 2 shows onesuch combination that is described in detail in Canadian PatentApplication No. 2,099,657, Alexander H. Rivers-Bowerman,‘Electrochemical Cell and Method of Manufacturing Same’, filed Jun. 25,1993. Additionally, a positive thermal coefficient device (PTC) may beincorporated into the header to limit the short circuit currentcapability of the battery. The external surface of the header 11 is usedas the positive terminal, while the external surface of the can 10serves as the negative terminal.

[0092] Appropriate cathode tab 6 and anode tab 7 connections are made toconnect the internal electrodes to the external terminals. Appropriateinsulating pieces 8 and 9 may be inserted to prevent the possibility ofinternal shorting. Prior to crimping the header 11 to the can 10 inorder to seal the battery, electrolyte 5 is added to fill the porousspaces in the jelly roll 4.

[0093] Those skilled in the art will understand that the types of andamounts of the component materials must be chosen based on componentmaterial properties and the desired performance and safety requirements.The compounds prepared in the examples to follow can have somewhatincreased irreversible capacity for lithium along with an increasedreversible capacity over that of many typical commercial carbonaceousanode materials. Also, the highest tap density of the example compoundsis still somewhat lower than that of typical commercial anode materials.This must be taken into account in the battery design. Generally anelectrical conditioning step, involving at least the first recharge ofthe battery, is part of the assembly process. Again, the determinationof an appropriate conditioning step along with the setting of thebattery operating parameters (eg. voltage, current, and temperaturelimits) would be required of someone familiar with the field.

[0094] Other configurations or components are possible for the batteriesof the invention (eg. prismatic format). A miniature embodiment, eg.coin cell, is also possible and the general construction of such cellsis described in the laboratory coin cell examples to follow.

[0095] Without wishing to be bound by theory, adversely or otherwise,the inventors offer the following discussion regarding this type of hardcarbonaceous host compound in order to explain how structuralcharacteristics relate to the electrochemical characteristics andtherefore what structural characteristics are desirable forelectrochemical applications. For overall simplicity, the followingdiscussion pertains to lithium insertion compounds. However, whereappropriate, similar comments apply for other alkali metals.

[0096] The presence of substantial hydrogen in carbonaceous materials ofthe prior art prepared by pyrolysis at low temperatures (between 550° C.and 750° C.) correlates with very high specific capacity but also withlarge hysteresis between insertion and extraction voltage. These effectsmay involve a binding of the inserted lithium and the hydrogen.

[0097] Hard carbonaceous materials having little hydrogen can stillexhibit specific capacities exceeding that of graphite however. Thegraphene sheets in the precursors for these hard carbonaceous materialsare cross-linked and this prevents the ordered stacking of layers in thegraphite structure as the precursors are pyrolyzed. When poorly stackedgraphene layers are present, it may be possible to adsorb lithium ontothe surfaces of each side of the layers. These surfaces are found withinthe carbon particles, on the atomic scale. In graphite, the layers arewell stacked in a parallel fashion and intercalation of lithium to acomposition of LiC₆ is possible (corresponding to about 370 mAh/g andone intercalated layer of lithium per graphene sheet). In materials withpoorly stacked layers, unshared lithium layers might possibly be foundon each side of the graphene sheets, resulting in compositions up toalmost Li₂C₆ (corresponding to about 740 mAh/g). Thus, the number ofsingle layer graphene sheets in the carbonaceous material may beimportant vis a vis specific capacity.

[0098] Information about the average number, N, of stacked graphenesheets in a carbon between serious stacking mistakes can be obtained byx-ray diffraction. This number N, multiplied by the average layerspacing is commonly given the name, L_(c). It may therefore be desirableto make carbonaceous materials with N about 1 and with very small L_(c)(eg. less than about 5 Å). The {002} Bragg peak measured in a powderx-ray diffraction experiment is normally used to determine L_(c) and N.For N=1, there is no {002} peak since there are no stacked parallelgraphene layers to create interferences. (Such a carbon sample might bethought of as having single graphene sheets arranged as in a ‘house ofcards’.) As N increases (beginning to stack the deck of cards), the{002} peak increases in height and decreases in width. Simultaneously,the background on the low angle side of the peak decreases, as Nincreases. Herein, the empirical parameter R is used for purposes ofdescribing such structures and can be used to distinguish the stackingorder in very disorganized materials. Materials having very small Rvalues (about 1) would have N values near 1. Materials having R near 5would have significantly larger N, possibly with N about 10. Thus,increases in R can be interpreted as increases in the average N in thesample.

[0099] The ‘house of cards’ structure of such disorganized carbonsimplicitly suggests the presence of significant voids or pores in thestructure. The pore number, size, and shape (particularly of theopenings) would be expected to relate to the ability of the single-layersheets to absorb lithium on both sides and also to have an impact on theelectrolyte accessible surface area. For instance, a relatively largenumber of single-layer sheets implies the existence of a relativelylarge number of ‘pores’ between sheets. The preferred pore size is largeenough to allow lithium to adsorb on both sides yet not to allow accessto non-aqueous electrolyte (a size in the nanometer scale).

[0100] Pores can be bottle shaped having neck openings that are smallenough to exclude electrolyte from the interior. However, the same porescan still have interiors that are large enough to easily accommodateelectrolyte. Samples having numerous such bottle shaped pores cantherefore have either relatively large or small surface area dependingon how it is measured. For example, if the pore opening is large enoughto admit nitrogen but not methylene blue, then nitrogen can be adsorbedon the interior pore surfaces whereas methylene blue cannot.Additionally, minor differences in the size of the pore openings canresult in dramatically different electrochemical results. Conceivably, asample could have enormous internal pore surface area (>>300 m²/g) asdetermined by BET that is inaccessible to the larger methylene bluemolecules. If the effective size of the non-aqueous electrolyte isintermediate to that of nitrogen and methylene blue, such a sample mighthave either an enormous or a negligible electrolyte accessible surfacearea depending on minor differences in the size of the pore openings.

[0101] A possible means of gradually increasing pore size and openingsthereof is by burning off small amounts by heating samples in an oxygencontaining atmosphere. (Previous studies on active carbon (J. S. Mattsonet al., Activated Carbon, Marcel Dekker Inc. NY, 1971 and F.Rodriguez-Reinoso et al., Chemistry and Physics of Carbon, Vol. 21,Edited by P. A. Thrower, p1) showed that both the sizes and shapes ofpores can be manipulated by physical and chemical activation processes.Note however that most activated carbons are not acceptable hostmaterials for electrochemical lithium insertion because the pore sizesare too large (on the micrometer scale)). Thus, oxidizing may be a meansfor incrementally increasing both the interior pore surface area and thecritical size of pore openings. Some results pertaining to this subjectare shown and discussed in the Illustrative Examples to follow.

[0102] Small angle x-ray scattering has been widely used for the studyof pore structure in carbons (see for example, H. Peterlik et al.,Carbon, 32 (1994) p.939). The presence of a substantial number ofmicropores results in substantial scattering of x-rays at small angle.Thus, carbonaceous hosts of the invention are expected to exhibit suchscattering. Conversely, the absence of such scattering is indicative ofthe absence of micropores (as shown in an Illustrative Example tofollow). Note that pores can be closed (ie. no openings) and materialscomprising such pores will still show substantial x-ray scattering.Thus, carbonaceous hosts can be imagined that have more pore volume,lower R values, and more small angle scattering, yet less lithiumcapacity and less irreversible capacity than a comparable host if manypores are closed.

[0103] The Guinier theory and formulae (in A. Guinier, Small-anglescattering of X-rays, Wiley and Sons, NY, 1955) can be used to determinepore sizes from the small angle scattering intensity assuminghomogeneous spherical pore sizes and randomly located pores. The radiusR_(s) of the pores is related to the radius of gyration, R_(g), by:

R_(g)=(3/5)^(½)R_(s).

[0104] The intensity, I_(q), at wavevector q is related to the radius ofgyration by:

I_(q)αNV²exp(−q²R_(g) ²/3)

[0105] where N is the number of pores and V is their volume. This theorytherefore predicts a straight line relationship between ln (I_(q)) andq². Although the aforementioned assumptions do not generally hold, sucha straight line relationship was observed in the case of the followingInventive examples. This suggests that these examples comprise pores ofapproximately uniform size. Generally speaking, uniform pore sizes; arepreferred since sizes at the small extreme (ie. in the range of thenormal interatomic distances) would contribute less to reversible alkalimetal capacity, while sizes at the larger extreme (ie. >30 Å) would bemore accessible to electrolyte leading to irreversible capacity (asshown in an Illustrative Example to follow).

[0106] A. Mabuchi et al., J. Electrochem. Soc., Vol. 142, No.4, April1995, show radii of gyration values derived from small angle scatteringdata for mesocarbon microbeads containing substantial hydrogen. Theeffective pore sizes are relatively very large (R_(g) of approximately37 Å and up) and the compounds exhibit significant hysteresis in theirvoltage curve upon insertion/extraction of lithium.

Background Information for the Examples

[0107] The following examples are provided to illustrate certain aspectsof the invention but should not be construed as limiting in any way.

[0108] In general, carbonaceous materials were prepared from hydrocarbonor polymer precursors by pyrolysis under inert gas. Unless otherwiseindicated, weighed amounts of the precursors were placed directly inalumina boats and inserted within a stainless steel or quartz furnacetube. The tube was flushed with inert gas for about 30 minutes and thenit was inserted into a tube furnace. The furnace and hence the sampletemperature was raised to the final pyrolysis temperature and held therefor one hour. The heating rate was sometimes deemed to be important, andin those cases the rate was carefully controlled using a programmabletemperature controller.

[0109] Powder x-ray diffraction was used to characterize samples using aSeimens D5000 diffractometer equipped with a copper target x-ray tubeand a diffracted beam monochromator. The diffractometer operates in theBragg-Brentano pseudofocussing geometry. The samples were made byfilling a 2 mm deep well in a stainless steel block with powder andlevelling the surface. The incident slits used were selected so thatnone of the x-ray beam missed the sample in the angular range from 10°to 35° in scattering angle. The slit width was fixed during themeasurement. This ensured reproducibility in the measured values of R.(Note: In certain Examples, R was determined slightly differently thanmentioned in the preceding. In the Inventive Examples pertaining toEpoxy and Phenolic Resin Precursors, Prior art Examples 1 and 2, and theIllustrative Example re Activated Carbons, the position of the {002}peak was taken to be that of the peak position including the backgroundrather than excluding the background. The effect on the determinedvalues of R is small for all practical purposes and is negligible in thefollowing Examples.)

[0110] Where indicated, small angle x-ray scattering data was collectedusing the preceding diffractometer operating in transmission geometry.Samples were prepared by filling a rectangular frame, having kaptonwindows, with powder. The prepared samples were about 1.5 mm thick. Theincident, antiscatter, and receiving slits were all set to their minimumvalues of 0.1°, 0.1°, and 0.1 mm respectively. Minimum scattering anglesof about 0.5° could be reached with this equipment, which corresponds toa wavevector q of about 0.035 Å⁻¹. The intensity scattered at 2θ=1° wasmeasured and divided by the sample mass to get a relative measure of thenumber of pores times volume² in the samples. This value was denoted I₁.R_(g) was determined using straight line fits to the small anglescattering data plotted as in (intensity) versus q² and theaforementioned formula.

[0111] Carbon, hydrogen, and nitrogen content was determined on samplesusing a standard CHN analysis (gas chromatographic analysis aftercombustion of the samples in air). The weight percents so determined hada standard deviation of ±0.3%. In every case, the carbon content wasgreater than 90% of the sample weight and the hydrogen content was lessthan 3.3%. The H/C atomic ratio was estimated by taking the ratio of thehydrogen and carbon weight percentages and multiplying by 12 (the massratio of carbon to hydrogen). The nitrogen content of all the sampleswas low and was not always reported. The oxygen content of the sampleswas not analyzed.

[0112] Where indicated, the absorption capacity for methylene blue (MB)was determined using a modification of conventional methods (as in theaforementioned reference Active Carbon). Samples were dried prior totesting at 130° C. In most or the following Examples, about 0.1 grams ofsample was placed in a flask along with 1-2 ml of 0.2% surfactantsolution (prepared using Micro-Liquid Laboratory Cleaner (trademark), astandard laboratory detergent) plus about 5 ml of deionized water. Atitration was then performed using a 1.5 g/L titrating solution ofhydrated MB in discrete steps. An initial amount of solution was addedfollowed by 5 minutes of vigorous shaking. (The initial amount waseither a minimum 0.1 ml or 1.0 ml depending on the estimated adsorptioncapacity of the sample.) The resulting mixture was then visuallycompared to a 0.4 mg/L reference solution of MB. If the mixture wasclearer than the reference, another 1.0 ml of titrating solution wasadded and the steps repeated. If the mixture was not clearer than thereference, adsorption was allowed to continue for a maximum of 3 days.If the mixture again became clearer than the reference, the discretetitrating continued. Otherwise, the measurement was finished and theadsorption capacity was taken to be that amount of MB titrated justbefore the last stepwise addition. For the samples tested, generally thetitrated MB was adsorbed in the 5 minute interval periods with theexception of the last few stepwise additions. In the CarbohydratePrecursor Examples and the Illustrative Examples re burnoff and smallangle scattering, the procedure was the same except that a 1 mMmethylene blue titrating solution was used and the stepwise additionswere not of constant magnitude.

[0113] Initially, conventional BET methods were tried in order todetermine the surface area of some hard carbon products based on theadsorption of nitrogen. The surface area could not be determinedreliably in this way however. During analysis, adsorption continuedslowly over long periods of time (hours). It seemed that the samples hadsubstantial surface area that was difficult, but possible, to accesswith nitrogen. Thus, the reliability of adsorption values was consideredquestionable using conventional BET methods. Instead, a modifiedprocedure was employed. Herein, single point BET surface areameasurements were made using a Micromeritics Flowsorb 2300 surface areaanalyzer. Carbon samples were outgassed under inert gas for severalhours at 140° C. before each measurement. The adsorption of nitrogen(from a 30% nitrogen in helium mixture) at 77° K on the samples wasallowed to proceed for several hours. Adsorption was considered completewhen the thermal conductivities of the gas stream before and after thesample were equal, indicating identical gas compositions. The amount ofN₂ adsorbed was determined by that which desorbed when the sampletemperature was increased to room temperature. Two measurements weremade for each sample and the results reported represent the average ofthe two desorptions. The measurements usually can be duplicatedsatisfactorily with an accuracy within ±3%. Standard methods were thenused to calculate the specific surface area of the sample accessible toN₂ molecules.

[0114] Where indicated, tap densities were measured using a QuantachromeDual Autotap device. Samples were placed in a 10 ml graduated cylinderand subjected to 500 standard taps.

[0115] Laboratory coin cell batteries were used to determineelectrochemical characteristics of the samples including specificcapacity for lithium. These were assembled using conventional 2325hardware and with assembly taking place in an argon filled glove box asdescribed in J. R. Dahn et al, Electrochimica Acta, 38, 1179 (1993).FIG. 3 shows an exploded view of the coin cell type battery. Forpurposes of analysis, the samples were used as cathodes in thesebatteries opposite a lithium metal anode. A stainless steel cap 21 andspecial oxidation resistant case 30 comprise the container and alsoserve as negative and positive terminals respectively. A gasket 22 isused as a seal and also serves to separate the two terminals. Mechanicalpressure is applied to the stack comprising lithium anode 25, separator26, and sample cathode 27 by means of mild steel disc spring 23 andstainless disc 24. The disc spring was selected such that a pressure ofabout 15 bar was applied following closure of the battery. 125 μm thickmetal foil was used as the lithium anode 25. Celgard® 2502 microporouspolypropylene film was used as the separator 26. The electrolyte 28 wasa solution of 1M LiPF₆ salt dissolved in a solvent mixture of ethylenecarbonate and diethyl carbonate in a volume ratio of 30/70.

[0116] Sample cathodes 27 were made using a mixture of powdered samplecompound plus Super S (trademark of Ensagri) carbon black conductivedilutant and polyvinylidene fluoride (PVDF) binder (both in amounts ofabout 5% by weight to that of the sample) uniformly coated on thincopper foil. The powdered sample and the carbon black were initiallyadded to a solution of 20% PVDF in N-methylpyrollidinone (NMP) to form aslurry such that 5% of the final electrode mass would be PVDF. ExcessNMP was then added until the slurry reached a smooth syrupy viscosity.The slurry was then spread on small preweighed pieces of Cu foil (about1.5 cm² in area) using a spreader, and the NMP was evaporated off atabout 90° C. in air. Once the sample cathode stock was dried, it wascompressed between flat plates at about 25 bar pressure. Theseelectrodes were then weighed and the weight of the foil, the PVDF, andthe carbon black were subtracted to obtain the active electrode mass.Typical electrodes were 100 micrometers thick and had an active mass of15 mg.

[0117] After construction, the coin cell batteries were removed from theglove box, thermostatted at 30±1° C., and then charged and dischargedusing constant current cyclers with ±1% current stability. Data waslogged whenever the cell voltage changed by more than 0.005 V. Unlessotherwise indicated, currents were adjusted to be 18.5 mA/g of activematerial for the initial two cycles of the battery. Much of thedischarge capacity of the example carbons is very close to the potentialof lithium metal. Thus, special testing methods were required todetermine the full reversible capacity. Coin cell batteries weretherefore discharged at constant current for a fixed time, the timebeing chosen such that the battery voltage would fall below zero volts(versus Li) and such that lithium plating on the carbon electrode wouldoccur. Note that the plating of lithium does not occur immediately afterthe battery voltage goes below zero volts due to the overvoltage causedby the finite constant current used. However, plating does begin shortlythereafter (usually around −0.02V) and is characterized by a regionwhere the voltage of the battery rises slightly once plating isinitiated followed by a constant or nearly constant voltage region. Theonset of lithium plating is clearly and easily determined as shown inthe following examples. The plating of lithium on the carbon electrodewas continued for a few hours and then the current was reversed. First,the plated lithium is stripped, and then inserted lithium is removedfrom the carbon. The two processes are easily distinguished providedthat the charge rates are small (ie. less than 37 mA/g of activematerial). The reversible capacity was calculated as being the averageof the second discharge and second charge capacities of the battery,excluding lithium plating and stripping. The first discharge capacitywas not used for this calculation because irreversible processes occuron the first discharge.

Illustrative Examples Re Prior Art Prior Art Example 1

[0118] Several samples were made by preparing a thermoset polymer fromfurfuryl alcohol in the presence of either phosphoric, oxalic, or boricacid followed by pyrolysis at various temperatures up to 1100°60 C.according to the methods of the aforementioned A. Omaru reference. Rvalues for all these samples were determined as mentioned above and theresults are listed in Table 1. TABLE 1 Data for the samples of Prior ArtExample 1. Pyrolysis temperature Presursor Polymerizing Acid (° C.) RPolyfurfuryl Alcohol Phosphoric 600 2.30 Polyfurfuryl Alcohol Phosphoric1100 2.45 Polyfurfuryl Alcohol Oxalic 900 2.56 Polyfurfuryl AlcoholPhosphoric 1000 2.74 Polyfurfuryl Alcohol Boric 900 4.9

[0119] The high capacity, hard carbon samples of the prior art appear tohave R values that exceed 2.2.

Prior Art Example 2

[0120] KSRAW grade (trademark) petroleum pitch was obtained from KurehaCompany of Japan in order to replicate the prior art material of Mabuchiet al. A series of soft carbon samples was made by pyrolysing said pitchat temperatures between 550° C. and 950° C. The H/C atomic ratios forthis series was determined as mentioned above and are shown in FIG. 4(also shown are H/C ratios for Inventive Example samples derived fromepoxy precursors to follow). The x-ray diffraction pattern in thevicinity of the {002} peak is shown in FIG. 5 for some of these samplesalong with the pattern of the precursor itself. (Note that the patternshave been offset vertically by 2000 counts for clarity.) R values andH/C data for this series are presented in Table 2. None of the sampleshave both R<2.2 and H/C<0.1. TABLE 2 Data for the samples of Prior ArtExample 2. Pyrolysis Temperature (° C.) H/C R 550 0.38 2.67 600 0.2352.14 700 0.183 2.33 900 0.080 3.33

[0121] Laboratory coin cell batteries were prepared using some of thesesamples as described previously. FIG. 6b shows the voltage versuscapacity plot for the second cycle of these batteries. (The plots havebeen shifted upwards sequentially by 0.05 V for clarity in FIG. 6b.)FIG. 6a shows an expanded version of FIG. 6b near 0 volts to betterindicate the onset of lithium plating and completion of lithiumstripping (indicated by arrows for the 550° C. data) during cycling.(The data have been shifted upwards sequentially by 0.1 V for clarity inFIG. 6a.)

[0122] Each of the samples pyrolyzed at 700° C. or less show a maximumspecific capacity (calculated as described previously) of about 650mAh/g. Samples pyrolyzed above 700° C. had significantly less capacity(down to about 400 mAh/g for the sample pyrolyzed at 900° C.).Substantial hysteresis in the voltage plots can be seen, especially forsamples pyrolyzed at the lower temperatures.

[0123] The very high capacity carbon samples of the prior art appear tolose their very high capacity characteristics when pyrolyzed attemperatures above about 700° C. There seems to be a correlation betweenlarger specific capacity and larger H/C ratio for these samples.

Illustrative Example Re Activated Carbons

[0124] M20E and M30 (trademarks) grade activated carbons were obtainedfrom Spectracorp, Mass., U.S.A.. Some of each activated carbon samplewas analyzed as is and some was pyrolyzed at 1000° C. prior to analysis.Additionally, polyvinylidene fluoride (PVDF, obtained from AldrichChemical company, U.S.A.) was pyrolyzed at 1000° C. R, H/C, CHN, andspecific capacity values were obtained as described in the preceding foreach of these samples. For each activated carbon sample, R was about 1.1and the H/C atomic ratio was very small (<0.03). FIG. 7 shows the x-raydiffraction pattern in the vicinity of the {002} peak for the M20Esample as received and after pyrolysis to 1000° C. For the pyrolyzedPVDF sample, R was about 1.3 and the H/C atomic ratio was 0.053.

[0125] The conventional BET surface areas for all these samples arerelatively high (>100 m²/g). Also, the adsorption capacity for MB isalso relatively high. For M20E and M30 activated carbons as supplied,the MB adsorption capacity exceeded 400 micromoles/g. (It was deemed tobe unnecessary to continue the titration.) The pyrolyzed PVDF carbonsample adsorbed about 200 micromoles of MB per gram.

[0126] All samples exhibited high specific capacities but alsosubstantial hysteresis in the voltage plot and substantial irreversiblecapacity on the first discharge. For instance, FIG. 8 shows the secondcycle voltage versus capacity plot for the battery containing M30activated carbon pyrolyzed at 1000° C. The specific capacity is about550 mAh/g and there is substantial hysteresis. FIG. 9 shows the firstcycle voltage versus capacity plot for the same battery containing M30activated carbon pyrolyzed at 1000° C. The first discharge capacity isenormous at about 2000 mAh/g and thus there is substantial irreversiblecapacity.

[0127] This example shows that some hard carbons, derived fromprecursors other than those of the invention, when pyrolyzed attemperatures above 700° C. can have R<2.2 and H/C<0.1 and yet notprovide the low hysteresis and irreversible capacity advantages of theinvention. Such hard carbons have high BET surface areas and also haverelatively high adsorption capacities for MB (>>4 micromoles/g carbon).

Inventive Examples

[0128] Epoxy Precursors:

Epoxy Example 1

[0129] A series of samples was prepared using Dow 438 (trademark of DowChemical Co., U.S.A.) epoxy novolac resin as a precursor. The resin wasusually mixed with different amounts of phthallic anhydride hardenerwhich was cured at about 120° C. to a hard plastic state prior topyrolysis. Pyrolysis was performed at temperatures varying from 700° C.to 1100° C. Afterwards, R, H/C, CHN, and specific capacity values wereobtained for most samples in the series as described in the preceding.Currents were adjusted to be either 7.4 mA/g, 18.5 mA/g, or 37 mA/g ofactive material, depending on the desired test. Conventional BET and MBadsorption capacities were also obtained for some representative samplesin the series. A summary of samples prepared with these correspondingvalues is shown in Table 3. TABLE 3 Data for the samples of EpoxyExample 1 Heating Pyrolysis Weight MB Specific Rate Temperature % WeightWeight Weight BET (μmoles Capacity No. (° C./min) (° C.) hardener % C. %H % N H/C (m²/g) per g) R (mAh/g) I 20 700 23 93.3 1.3 <0.1 0.17 NA NA1.39 6.50 II 20 800 23 91.7 0.85 <0.1 0.11 NA <4 1.43 6.10 III 20 900 2393.4 0.52 <0.1 0.067 NA NA 1.47 5.90 IV 20 1000 23 95.2 0.50 0.2 0.063NA NA 1.59 NA V 1 1000 0 95.4 0.26 0.5 0.033 >152 <4 2.10 475 VI 1 100015 95.4 0.69 0.5 0.087 NA NA 2.32 455,430 VII 10 1000 38 93.1 0.23 0.60.030 >217 <4 1.42 570 VIII 1 1000 15 95.8 0.41 0.4 0.051 NA <4 1.90430,440 IX 5 1000 15 97.3 0.20 0.2 0.025 NA NA 2.92 280

[0130] The voltage versus capacity plots for sample no. I pyrolyzed at700° C. is compared to that of the pitch sample of Prior Art Example 2pyrolyzed at the same temperature in FIG. 10. These two plots showalmost identical behaviour (although the battery using sample no. I wasallowed to plate more lithium). FIG. 4 indicates that the two samples inFIG. 10 have almost the same H/C ratio. FIG. 11 shows the x-raydiffraction patterns of samples no. I, II, and III (offset by 1600counts). Therein, it can be seen that sample no. I has a substantiallysmaller R than the corresponding pitch sample in FIG. 5. There are veryfew stacked graphene layers in sample no. I as evidenced by the {002}peak amounting to only a shoulder on the low angle background. FIGS. 11and 5 also show that these structural differences persist at higherpyrolysis temperatures.

[0131]FIGS. 12a and b show the voltage versus capacity plots for samplesno. I, II, III, and V (plots are offset by 0.05 and 0.1 volts in Figuresa and b respectively). These samples all have R<2.2. Sample I showsconsiderable hysteresis in the voltage plot. At higher pyrolysistemperatures, the capacity available near 1.0 V during the charge ofsample no. I is shifted down to near 0 V, so that around 900° C. to1000° C. reversible cycling with little hysteresis is obtained.Furthermore, high specific capacity is maintained in samples no. III andV at pyrolysis temperatures of 900° C. to 1000° C., unlike that of thepyrolyzed pitch of Prior Art Example 2.

[0132]FIGS. 13a and b show the voltage versus capacity plots for samplesno. V, VI, VII, and IX (plots are offset by 0.05 and 0.1 volts inFigures a and b respectively). These Figures also illustrate therelation between R and specific capacity for samples pyrolyzed at 1000°C. to 1100° C. As R increases, the specific capacity decreases. FIG. 14shows the x-ray diffraction patterns in the vicinity of the {002} peakfor the samples of FIGS. 13a and b. (The patterns have been offsetupwards sequentially by 3000 counts for clarity.) FIG. 15 is provided toshow a summary plot of specific capacity versus R for samples III to IXinclusive which were all pyrolyzed between 900° C. and 1100° C. Thesamples therein all exhibited voltage curves with little hysteresis andall had H/C<0.1. Again, as R increases, the specific capacity decreases.

[0133]FIG. 16 shows the first discharge and charge of the laboratorycoin cell battery employing sample no. VII. The battery shows a firstdischarge capacity of about 625 mAh/g and a first recharge capacity ofabout 465 mAh/g. The irreversible capacity of sample VII is thereforeonly about 160 mAh/g, which is considered to be in an acceptable rangefor practical lithium ion batteries. The surface area measured by theconventional BET method for sample VII was 217 m²/g. If this area wereall accessible to electrolyte, such low values for the irreversiblecapacity would not be expected (for example, based on the disclosure ofU.S. Pat. No. 5,028,500). However, the MB adsorption capacity isrelatively low (<5 micromoles/g) for this and all the other inventivesamples tested.

[0134] Insertion compounds of the invention can therefore have very highspecific capacity coupled with acceptable associated hysteresis involtage and acceptable associated irreversible capacity.

Epoxy Example 2

[0135] A sample was prepared using Dow D.E.R. 667 (trademark of DowChemical Co., U.S.A.) bisphenol A type epoxy resin as a precursor. Nohardener was used in this preparation. Pyrolysis was performed byheating first at 250° C. for 2 hours followed by ramping at 30° C./minto 800° C. and thereafter holding for 2 hours. R for this sample wasabout 1.52. Laboratory coin cell batteries were then prepared andspecific capacity values were obtained.

[0136] The voltage versus capacity plot for one of these batteries isshown in FIGS. 17a and b (plots are offset by 0.05 and 0.1 volts inFigures a and b respectively). Therein, the specific capacity was 410mAh/g. The irreversible capacity is only about 160 mAh/g and thehysteresis in the voltage is considered acceptable.

[0137] It thus appears possible to make insertion compounds of theinvention using bisphenol A type epoxy resin.

[0138] Phenolic Resin Precursors:

Phenolic Resin Example 1

[0139] A series of samples was prepared using three different phenolicresins as a precursor. Two are base-catalysed or resole types and one isan acid catalyzed or novolac type. The three different precursors usedwere:

[0140] A) resole type, product #11760 of Plenco, Plastics EngineeringCompany, Sheboygan, Wis., 53082-0758 U.S.A.;

[0141] B) resole type, product it #29217 of Oxychem, Occidental ChemicalCorp, Durez Engineering Materials, 5005 LBJ freeway, Dallas, Tex. 75244,U.S.A.; and

[0142] C) novolac type, product #12116 of Plenco, supra.

[0143] The phenolic resin precursors were all supplied in powder form.In each case, the powder was cured at from about 150° C. to 160° C. for30 minutes prior to pyrolysis. At the end of the curing step, a solidlump was obtained. The lump was next reduced to powder in anautogrinder. The powdered cured resin was then pyrolyzed in a tubefurnace under flowing argon. The samples were ramped from roomtemperature to the desired pyrolysis temperature over 3 hours and heldthere for 1 hour. The furnace power was then turned off and the sampleswere cooled to near room temperature within the furnace tube underflowing argon. Cooling took several hours.

[0144] Pyrolysis was performed at temperatures varying from 700° C. to1100° C. Afterwards, the samples were ground into a powder. R, H/C (byCHN analysis), and specific capacity values (by coin cell battery tests)were obtained for most samples in the series as described in thepreceding. The MB adsorption capacity was also obtained for sample B1000and was found to be about 1.6 micromoles per gram of host. Yield wasdetermined from the weights of the samples before and after pyrolysis.The results of these measurements is given in Table 4. (Two batteries ofeach sample were made and the results from each experiment were within20 mAh/g. The values given in Table 4 represent the average valuesobtained.) TABLE 4 Data for the samples of Phenolic Resin Example 1Reversible Irreversible Pyrolysis Capacity Capacity Sample Temp. WeightWeight Weight Yield (mAh/g) (mAh/g) ID (° C.) % C % H % N H/C (%) R(±20) (±20) A700 700 91.2 1.5 1.2 0.19 57 1.37 500 440 A800 800 93.1 1.01.3 0.13 55 1.56 510 280 A900 900 92.3 0.6 1.2 0.07 55 1.63 510 210A1000 1000 94.2 0.4 1.9 0.05 54 1.68 450 160 A1100 1100 96.7 0.3 0.80.04 52 1.79 330 70 B700 700 94.7 1.8 0.4 0.22 58 1.33 630 260 B800 80095.8 0.9 0.7 0.11 57 1.39 540 210 B900 900 94.8 0.5 0.5 0.06 57 1.32 410300 B1000 1000 95.6 0.3 0.6 0.04 56 1.34 560 200 B1100 1100 97.4 0.4 1.40.05 56 1.64 340 110 C800 800 95.7 0.9 0.6 0.11 64 1.53 530 210 C900 90095.1 0.4 0.7 0.05 57 1.63 450 180 C1000 1000 96.5 0.3 0.8 0.04 58 1.54450 130 C1100 1100 97.0 0.3 1.3 0.03 56 1.64 330 120

[0145]FIG. 18a shows the first discharge-charge cycle for the series ofpyrolyzed A type precursors. The samples heated at 700° C. and 800° C.show significant hysteresis in the voltage profile (Li is inserted near0V but is removed near 1.0V). This has been ascribed to the largehydrogen content in the samples. Upon heating to 900° C., the hysteresisis predominantly eliminated and the samples show substantial capacity atlow voltage. FIG. 18b shows the second cycle of the same series. Thevertical lines indicate the onset of lithium plating during dischargeand the termination of lithium stripping during charge. The batteriesprepared from material heated to 900° C. and 1000° C. appear mostpromising for this series. Their reversible capacities are about 510 and450 mAh/g respectively.

[0146]FIGS. 19a and 19 b show the first and second cycle voltageprofiles for the series of pyrolyzed B type precursors. The sample madeat 1000° C. gives a reversible capacity of about 560 mAh/g and anirreversible capacity of only about 200 mAh/g. This is a very attractivematerial for use as a lithium ion battery anode. FIGS. 20a and 20 b showthe first and second cycle voltage profiles for the series of pyrolyzedC type precursors. The samples made at 900° C. and 1000° C. givereversible capacities near 450 mAh/g. The latter has an irreversiblecapacity of only 130 mAh/g.

[0147] Extended cycling was carried out on a battery comprising sampleB1000 at currents of 37 mA/g of active material. FIG. 21 shows thecapacity versus cycle number for this battery. There is little capacityloss upon cycling.

[0148] Insertion compounds of the invention can therefore have highreversible specific capacity coupled with acceptable associatedhysteresis in voltage and acceptable associated irreversible capacity.

Phenolic Resin Example 2

[0149] The series of samples made from the B type precursor were shownto have the highest reversible capacities in the preceding Example. Inorder to determine how the reversible and irreversible capacities variedin the narrower temperature range between 900° C. and 110° C., anadditional series of samples using this precursor was prepared. Thesamples were tested in coin cell batteries as described earlier andvoltage profiles, irreversible capacities, and reversible capacitieswere measured. Two batteries of each were made and the results from eachexperiment were within 20 mAh/g.

[0150] Table 5 summarizes the average specific capacity results for allthe samples prepared from the B type precursor. FIG. 7 showsrepresentative second cycle voltage profiles for the batteries made withthese samples. TABLE 5 Data for the samples of Phenolic Resin ExamplesReversible Capacity Irreversible Capacity Sample ID (mAh/g) (±20)(mAh/g) (±20) B900 410 300 B940 470 160 B970 550 160 B1000 560 200 B1030540 140 B1060 450 200 B1100 340 110

[0151] Appropriate selection of the pyrolysis temperature appears to beimportant in order to optimize the properties of these insertioncompounds.

[0152] Carbohydrate and Carbohydrate Containing Precursors:

[0153] Carbonaceous hosts of the invention were prepared using a varietyof carbohydrate precursors. Table 6 lists the precursors used, alongwith their source and morphology. TABLE 6 List of carbohydrateprecursors Carbohydrate Material Supplier Morphology Table Sugar CanadaSafeway Powder (sucrose) Sucrose BDH Inc. (Toronto), Powder Reagentgrade Starch BDH Inc. (Toronto) Powder Reagent grade Walnut ShellsCanada Safeway Small pieces of shell separated from the nut FilbertShells Canada Safeway Small pieces of shell separated from the nutAlmond Shells Canada Safeway Small pieces of shell separated from thenut Red Oak Reimer Hardwoods 1 cm³ chunks cut from (Abbotsford, B.C.)furniture-grade lumber Maple Reimer Hardwoods 1 cm³ chunks cut from(Abbotsford, B.C.) furniture-grade lumber

[0154] Precursors (typically batches between 1 and 25 grams) werecontained in nickel foil boats and placed within a stainless steel orquartz furnace tube. Prior to heating, the tube was flushed with argon(Ultra High Purity Grade—Linde) for 30 minutes to remove air. Thesamples were heated from room temperature to a desired pyrolysistemperature at a rate of 25° C./min. They were held at the pyrolysistemperature for 1 hour. The furnace power was then turned off and thesamples were cooled to near room temperature within the furnace tubeunder flowing argon (a process which took several hours). The sampleswere weighed before and after pyrolysis, so that the yield could bedetermined. Certain samples were pyrolyzed at temperatures of 1200° C.and higher. These samples were first pyrolyzed to 1100° C. as in thepreceding. Thereafter, pyrolysis was continued in a similar manner usinga Centorr Series 10 furnace.

[0155] Some samples of table sugar (hereinafter denoted simply as‘sugar’) were precarbonized by washing in excess concentrated sulfuricacid. About 50 grams of sugar was first mixed with about 100 cc ofconcentrated sulfuric acid, added slowly. The resulting char was brieflycrushed, washed with boiling water, and filtered to recover the solids.Rinsing was repeated until the filtrate gave the same pH (about 6) asthe tap water used for rinsing. The product was dried overnight at 110°C. overnight before pyrolysis. The carbon yield was calculated for thesesamples by the final carbon mass divided by the initial weight of sugar.These samples are denoted as ‘a-sugar’ samples.

[0156] The pyrolyzed samples were ground to powder and analyzed asdescribed in the preceding. Results of these measurements are tabulatedin Table 7. TABLE 7 Summary of characteristics of pyrolyzed carbohydrateprecursors Irrev- ersible Capa- Pyrolysis I_(I) Tap MB SurfaceReversible city** Temp. Yield C H N H/C (counts Density (μmoles areaCapacity** (±20 No. Precursor (° C.) % wt. % wt % wt. % atomic RR_(g)(A) per mg) (g/cc) per mg) (m²/g) (±20 mAh/g) mAh/g) 1 sugar 110012* 97.3 0.28 0.96 0.034 1.91 5.49 19.3 0.69 — 15 537, 534 130, 141 2sucrose 1000 8* 96.9 0.42 0.67 0.05 1.96 5.32 16.7 0.91 <2.9 31 529, 534138, 137 3 sugar 1000 11* 97 0.51 0.72 0.063 1.95 5.49 18.4 — — 220 442,363 205, 222 4 sugar 900 12* 95.5 0.59 0.39 0.074 1.75 4.82 11.9 0.78 —58 590, 557 175, 184 5 sugar 800 17* 95.2 0.94 0.27 0.12 1.76 4.74 100.8 — 120 624, 623 197, 212 6 sugar 700 12* 93.8 1.41 0.21 0.18 1.58 413.3 0.62 — 250 690, 740 274, 266 7 sugar 600 14* 92.5 2.28 0.1 0.3 1.463.13 6.8 0.67 — 460 764, 790 455, 313 8 a-sugar 1100 27 97.2 — 0.25 —1.63 5.01 15.8 — <1.5 1.8 564, 567 34, 75 9 a-sugar 1000 30 97 0.49 0.360.061 1.78 5.27 16.2 — — 180 477, 460 130, 147 10 a-sugar 900 29 95.40.55 0.42 0.069 1.69 4.8 11.3 — — 68 591, 605 182, 188 11 a-sugar 800 2994.3 0.93 0.28 0.12 1.64 4.71 10.5 — — 490 577, 566 225, 220 12 a-sugar700 30 91.4 1.51 0.26 0.2 1.47 4.37 8.6 — — 430 577, 575 375, 378 13a-sugar 600 30 92.9 2.41 0.21 0.31 1.3 3.08 6.5 — — 370 665, 706 521,466 14 starch 1000 11 91.7 0.52 0.84 0.068 1.88 5.7 23.2 0.76 <2.5 30493, 496 196, 199 15 filbert 1000 23 — — — — 1.92 5.72 22.7 0.63 — 180412, 400 183, 198 16 walnut 1000 23 — — — — 1.85 5.97 16 0.63 — 60 490,490 157, 126 17 almond 1000 23 — — — — 2 5.93 17 0.6 — 46 395, 371 167,185 18 oak 1000 18 — — — — 1.85 5.53 19.1 0.54 <3.5 13 518, 515 145, 15919 maple 1000 18 — — — — 1.98 5.58 28.2 0.56 — 63 497, 503 140, 127 20maple 1100 18 — — — — 1.86 5.54 20.0 0.56 — 11 547, 524  —, 104 21 sugar1200 11* — — — — 1.98 5.66 22.5 0.60 — 5.5 374, 379 71, 59 22 sugar 140011* — — — — 2.37 6.08 31.5 0.63 — 7.9 284, 296 35, 38 23 sugar 1600 11*— — — — 3.09 6.53 46.7 0.58 — 6.3 208, 210 31, 34 24 a-sugar 1200 28 — —— — 1.83 5.78 17.3 0.77 — 1.3 367, 368 38, 45 25 a-sugar 1400 28 — — — —2.02 5.95 21.8 0.76 — 1.2 280, 274 25, 25 26 a-sugar 1600 28 — — — —2.48 6.46 33.2 0.73 — 1.2 198, 202 24, 25 27 starch 1100 11 — — — — 1.885.59 29.6 0.71 — 4.9 523, 526 154, 150 28 starch 1200 10 — — — — 2.136.06 42.6 0.65 — 3.1 337, 389 58, 54 29 starch 1400 10 — — — — 2.40 6.2142.8 0.58 — 3.8 277, 286 32, 30 30 starch 1600 10 — — — — 2.89 6.66 65.40.55 — 3.3 212, 207 35, 32 31 oak 1100 19 — — — — 1.78 5.47 19.5 0.59 —12.1 587, 538 115, 120 32 oak 1200 18 — — — — 2.02 5.94 30.9 0.55 — 4.8334, 330 38, 60 33 oak 1400 18 — — — — 2.26 6.11 35.5 0.55 — 4.7 261,270 33, 35 34 oak 1600 18 — — — — 2.66 6.58 46.8 0.53 — 4.6 192, 197 30,29

[0157] Yields near 20% were readily achieved using this simple pyrolysismethod. The H/C ratio was less than 0.1 for heating temperatures above800° C. Tap densities up to 0.9 g/cc were obtained.

[0158]FIG. 23 shows the powder x-ray diffraction profiles of somepyrolyzed sucrose samples (numbers 1, 2 (BDH source), 4, 5, 6, and 7) asa function of pyrolysis temperature. The {002} Bragg peak near 22° ispoorly formed in all these samples, indicating materials made uppredominantly of single carbon layers arranged somewhat like a ‘house ofcards’. The {100} and {110} Bragg peaks near 44° and 80° respectivelycan be used to estimate the lateral extent of the graphene sheets (thisis the distance over which the sheets are more or less flat). Thelateral dimension ranges from near 10 Å for the sample pyrolyzed at 600°C. to near 25 Å for the sample pyrolyzed at 1100° C. The diffractionpatterns for the samples made from acid-washed sugar (numbers 8-13) showsimilar features.

[0159]FIG. 24 shows the x-ray diffraction profiles for the samplespyrolyzed at 1000° C. from starch and cellulose precursors. The patternsshown are for samples number 18, 17, 16, 15, and 14 from top to bottomin FIG. 24. These patterns resemble one another and additionallyresemble the pattern of sample number 2 in FIG. 23, suggesting similarstructural arrangements.

[0160] Higher pyrolysis temperature tends to produce smaller BET surfacearea. (However, samples number 3 and 9 have anomalously high surfaceareas.) During pyrolysis, the samples emit water, CO₂, and other gases.If the argon flow rate is too small, these gases remain in the tube andoxidize the samples leading to high surface areas.

[0161] Laboratory coin cell batteries were constructed using thesepyrolyzed samples as described in the preceding. FIGS. 25a and b showthe voltage versus capacity plots for the second cycle forrepresentative batteries comprising samples number 8, 2, 10, 11, and 12prepared between 700° C. and 1100° C. Samples number 8, 2 ,and 10 showlarge reversible capacities and little voltage hysteresis. (Materialsprepared at 800° C. and below can contain substantial hydrogen leadingto significant hysteresis in the voltage plateaus. Nevertheless, suchcarbons, if prepared cheaply enough, might be useful for some batteryapplications.)

[0162] From the data in Table 7, irreversible capacities are seen todecrease as the pyrolysis temperature increases. Samples number 3 and 9have significantly less reversible capacity than does sample 2, preparedat the same temperature. This might be attributed to differences in thesamples as evidenced by the larger surface area of samples 3 and 9compared to sample 2.

[0163]FIGS. 26a and b show the voltage versus capacity plots for thesecond cycle for representative batteries made with sucrose, cellulose,and starch precursors pyrolyzed at 1000° C. Data is shown for samplenumber 2 (for comparison), 18 (oak), 14 (starch), 16 (walnut shells) and15 (filbert shells). Samples 2, 18, and 14 show excellent behavior, andit is likely that the performance of the other samples could be improvedthrough changes to the pyrolysis process. Thus, pyrolyzed products madefrom oak, starch, and walnut shells gave similar behavior to that madefrom sucrose.

[0164] Some of the batteries underwent extended cycling as described inthe preceding. Discharge and charge currents of 74 mA/g and 37 mA/grespectively were used for the extended cycle testing between 2.0V andthe onset of lithium plating. FIGS. 27, 28, and 29 show the capacityversus cycle number for batteries containing electrodes of samples 8,14, and 18 respectively. These batteries show little capacity loss uponcycling and retain cycling capacities near 500 mAh/g. The batterycontaining sample 14 (FIG. 28) shows the poorest performance. This maybe due to the large impurity content in the sample (as per Table 7, thissample is only 91.7% carbon by weight).

[0165] Thus, carbohydrates in general can be used to prepare insertioncompounds having excellent electrochemical characteristics by pyrolyzingat temperatures between about 800° C. and about 1200° C. Somedifferences were noticed between the samples prepared from differentcarbohydrate precursors, but these may be due in part to the differingamounts of impurities in the naturally occurring sources. For example,the wood and shell samples comprise significant, varied amounts oflignin and/or oil.

Comparative Example

[0166] For purposes of comparison, the characteristics of sample numberVII from Epoxy Resin Example 1 and sample B1000 from Phenolic ResinExample 1 are reported in Table 8 below. TABLE 8 Characteristics ofComparative Examples I_(I) MB Surface Reversible Irreversible Sample(counts (μmoles area Capacity Capacity Number H/C R R_(g) per mg) per g)(m²g) (mAh/g) (mAh/g) VII 0.03 1.58 5.7* 14* <4 217 570 150 (epoxy)B1000 0.04 1.37 5.5 10 — 235 560 200 (phenolic resin)

[0167] Voltage curves of cycles 5 and 6 of the batteries comprisingcarbohydrate precursor sample 8 and phenolic resin precursor sampleB1000 are shown in FIG. 30. (The B1000 sample was discharged and chargedat 37 mA/g.) The curves are similar. FIG. 31 compares the differentialcapacity, measured during the 5th cycle charging, of the two batteriesof FIG. 30. Within error, these are identical.

[0168] The insertion compounds prepared from pyrolyzed epoxy resins,phenolic resins, and/or carbohydrates can have the same physical andelectrochemical characteristics.

Illustrative Examples re Burnoff

[0169] A first amount of DEN 438 epoxy novolac resin (from DOW Chemical)was cured with 20 weight % 4-aminobenzoic acid at 170° C. and pyrolyzedat 1000° C. to produce carbon-aceous material similar to sample numberVII of the Epoxy Examples. Samples (about 1 gram each) were thenoxidized to varying degrees in a furnace tube under a flow of extra dryair. This was accomplished by heating the samples at a rate of 10°C./minute to different specific maximum temperatures (T_(max)). Theamount of carbon burned off was obtained by calculating the differencebetween the initial and final mass (accurate to ±0.1%).

[0170]FIG. 32 shows the x-ray diffraction patterns of three of thepreceding oxidized samples with varying weight % burned off. Theintensity of the diffraction peaks decreases with % burnoff while theintensity at small scattering angles increases with % burnoff. Thediffraction peaks may be expected to decrease as the number of x-rayscatterers decreases. The increase in intensity at small angles isconsistent with an increase in porosity of the sample. The ln(intensity) versus q² relationship was roughly linear in each case, andthe derived values of R_(g) also suggest a small increase in pore sizewith % burnoff.

[0171] A second amount of DEN 438 epoxy novolac resin (from DOWChemical) was cured with 20 weight % phthalic anhydride at 170° C. andthen pyrolyzed at 1000° C. to produce carbon-aceous material similar tosample number VII of the Epoxy Examples. Samples (about 1 gram each)were then oxidized to varying degrees in a furnace tube under a flow ofextra dry air. This was accomplished by heating the samples at a rate of10° C./minute to different specific maximum temperatures (T_(max)). Theamount of carbon burned off was obtained by calculating the differencebetween the initial and final mass (accurate to ±0.1%). Physical andelectrochemical characteristics were determined as in the precedingInventive Examples. Table 9 shows a summary of the values obtained. (Thespecific reversible and irreversible capacities represent the averagevalue determined from two test batteries.)

[0172] This second set of pyrolyzed samples was then reheated at 1000°C. under argon to remove surface oxides. The weight loss after thisreheating is also shown in Table 9. Where indicated, the specificcapacities of the reheated samples were also determined.

[0173] The surface area as determined by BET increased markedly withburnoffs of only a few weight %. Also, there were significantdifferences noticed in the nitrogen adsorption kinetics. It tookprogressively less time for samples to fully adsorb nitrogen (from about4 hours for sample I-1 down to less than 1 hour for sample I-8). Bycontrast, the MB absorption values did not increase significantly untilafter about 5% by weight was burned off. As pore openings enlarge or asnew openings are created, the rate and total amount of nitrogen adsorbedmay be expected to increase. A corresponding increase in the amount ofMB absorbed may be delayed until pore openings enlarge enough to admitthe larger MB molecules.

[0174]FIGS. 33a (magnified view) and b show the voltage versus capacityplots for the second cycle of representative batteries comprising thepreceding samples. Samples I-1 and I-2 exhibit a low voltage plateauhaving substantial capacity (about 200 mAh/g). The capacity of thisplateau decreases quickly with % burnoff and is virtually eliminated byabout 5% burnoff. As shown in Table 9, the reversible capacity decreasesinitially with % burnoff, and then increases above about 10% burnoff.Surface oxide complexes formed during the oxidation process may accountfor this subsequent increase in capacity. Close examination of thevoltage plots for samples I-6 and I-8 in FIG. 33b shows that thissubsequent increase is associated with lithium insertion near zero voltsand extraction above one volt (ie. with substantial hysteresis in thevoltage curve). Such high hysteresis capacity is generally unsuitablefor lithium ion battery applications.

[0175] The irreversible capacity increases with burnoff % approximatelylinearly with the BET surface area and beginning well before the MBabsorption values start to increase. This suggests that the electrolytemolecules are accessing pore surfaces before the MB do (ie. electrolytemolecules are smaller than MB molecules).

[0176] The weight loss for the reheated samples is greatest for sampleI-6 indicating that the amount of surface oxides is greatest for thissample. Qualitatively, this agrees with previous work in the literaturewherein higher temperature oxidation results in fewer surface oxides.Upon reheating, both the reversible and irreversible capacity of thesamples are reduced up to about 100 mAh/g, suggesting that the surfaceoxides play a role in both. The low voltage plateau, present in sampleI-1, is not recovered after reheating, even for sample I-3 having only1.2% burned off by weight. Thus, even minimal oxidation can seriously,and irreversibly, degrade the performance of the compounds of theinvention. The presence of surface oxides can indicate that suchoxidation occurred. In turn, an observed weight loss upon heating acarbon sample under inert gas can indicate the presence of such surfaceoxides.

[0177] Additionally, the preceding illustrates the difficulties inquantifying electrolyte accessible surface areas using nitrogen ormethylene blue molecules as substitutes for the electrolyte itself. Ifthe latter is intermediate in size to the former, a sample can have anacceptable MB absorption value but still not exhibit the advantages ofthe invention (eg. sample I-3). Conversely, an acceptable limit for theBET surface area is difficult to define since a sample can conceivablyhave an enormous internal surface area that is accessible by nitrogenbut not electrolyte (Note that carbons having the advantages of theinvention with BET surface areas as high as 212 m²/g were made in thepreceding Epoxy Examples. Sample I-3, with a 316 m²/g surface area, onthe other hand does not have the advantages of the invention.) TABLE 9Summary of characteristics of oxidized samples Reversible IrreversibleBurnoff I_(I) MB Surface Reversible Irreversible Weight Loss Capacityafter Capacity after Sample T_(max) Amount R_(g) (counts (μmoles areaCapacity Capacity % after reheating reheating No. (° C.) % R (A) per mg)per g) (M²/g) (mAh/g) (mAh/g) reheating (mAh/g) (mAh/g) I-1 25 0.0 1.975.7 14.0 2.3  63 ± 5 461 122 1.5 — — I-2 300 0.7 2.00 5.9 15.2 2.3  104± 15 459 171 2.8 — — I-3 400 1.2 2.00 6.1 19.2 1.9 316 ± 8 331 365 7.0305 240 I-4 452 5.1 2.26 6.0 16.9 5.2 384 ± 2 316 487 10.6 — — I-5 48412.5 2.23 6.3 22.6 16.6 553 ± 3 370 456 12.5 — — I-6 525 28.2 2.10 6.843.3 27.1 579 ± 2 404 529 13.4 305 484 I-7 550 34.0 2.13 6.7 35.8 28.1591 ± 2 397 526 10.7 — — I-8 600 54.6 2.07 6.8 41.6 39.5 797 ± 5 456 5467.1 — —

Illustrative Example Re Small Angle Scattering

[0178] Three precursor materials, i) polyvinylidene fluoride (PVDF), ii)Crowley pitch (tradename), and iii) phenolic resole resin (product no.29217 from Occidental Chemical Corp.), were pyrolyzed at 1000° C. andsmall angle x-ray scattering data was obtained on each as describedabove. FIGS. 34a and b show plots of the intensity versus scatteringangle and ln (intensity) versus q² respectively for each sample. Theresole resin sample shows significant scattering (intensity) at smallangles and the data in FIG. 34b is linear, suggesting that the internalpores are predominantly uniform in size. The data can thus be fit to theGuinier formula giving R_(g)=5.5 Å. The resole resin sample is similarto the B1000 sample from the Phenolic Resin Examples which shows all thedesirable electrochemical characteristics of the instant invention.

[0179] The pyrolyzed PVDF sample also shows significant scattering atsmall angles but the data in FIG. 34b is non-linear, suggesting thepresence of a variety of pore sizes including pores larger than those ofthe pyrolyzed phenolic resole resin The H/C atomic ratio for this samplewas 0.053, R was 1.23, and the amount of methylene blue absorbed wasgreater than 40 micromoles per gram. The reversible and irreversiblelithium capacities were 380 mAh/g and 710 mAh/g respectively. Thissample has an unacceptably large electrolyte accessible surface area.

[0180] The Crowley pitch (tradename) sample shows minimal small anglescattering indicating that this sample has minimal porosity. Thephysical and electrochemical characteristics of this sample are similarto those of other pyrolyzed cokes. (The H/C atomic ratio for this samplewas 0.04 and R was 8.79. The reversible and irreversible lithiumcapacities were 340 mAh/g and 100 mAh/g respectively.)

[0181] As will be apparent to those skilled in the art in the light ofthe foregoing disclosure, many alterations and modifications arepossible in the practice of this invention without departing from thespirit or scope thereof. For example, mixtures of more than oneprecursor may be used to prepare compounds. Additionally, carbohydrateprecursors might contain significant matter that is not a carbohydrate,as in the case of wood, shells, cotton or straw. Accordingly, the scopeof the invention is to be construed in accordance with the substancedefined by the following claims.

What is claimed is:
 1. A carbonaceous insertion compound comprising: apre-graphitic carbonaceous host having a reversible capacity for lithiuminsertion, an irreversible capacity for lithium insertion, and a surfacearea accessible to a non-aqueous electrolyte wherein i) the empiricalparameter R, as determined by x-ray diffraction and defined as theheight of the centre of the {002} peak divided by the background level,is less than about 2.2; ii) the H/C atomic ratio is less than about 0.1;and iii) the accessible surface area is sufficiently small such that theirreversible capacity is less than about a half that of the reversiblecapacity; and alkali metal atoms inserted into the carbonaceous host. 2.A carbonaceous insertion compound as claimed in claim 1 wherein thealkali metal is lithium.
 3. A carbonaceous insertion compound as claimedin claim 1 wherein the accessible surface area is sufficiently smallsuch that the irreversible capacity is less than about a third that ofthe reversible capacity.
 4. A carbonaceous insertion compound as claimedin claim 1 wherein the methylene blue absorption capacity of thecarbonaceous host is less than about 4 micromoles per gram of host;
 5. Acarbonaceous insertion compound as claimed in claim 1 wherein thesurface area of the carbonaceous host as determined by BET is less thanabout 300 m²/gram.
 6. A carbonaceous insertion compound as claimed inclaim 1 wherein less than about 5% by weight of the carbonaceous host islost after pyrolyzing at about 1000° C. under inert gas.
 7. Acarbonaceous insertion compound as claimed in claim 1 wherein thenon-aqueous electrolyte comprises ethylene carbonate and diethylcarbonate.
 8. A carbonaceous insertion compound as claimed in claim 1wherein R is less than about
 2. 9. A carbonaceous insertion compound asclaimed in claim 1 wherein R is less than about 1.5.
 10. A carbonaceousinsertion compound comprising: a pre-graphitic carbonaceous hostprepared by pyrolyzing an epoxy precursor, a phenolic resin precursor, acarbohydrate precursor or a carbohydrate containing precursor at atemperature above 700° C. wherein the empirical parameter R, determinedfrom an x-ray diffraction pattern and defined as the {002} peak heightdivided by the background level, is less than about 2.2; and alkalimetal atoms inserted into the carbonaceous host.
 11. A carbonaceousinsertion compound as claimed in claim 10 wherein the H/C atomic ratioof the pre-graphitic carbonaceous host is less than about 0.1.
 12. Acarbonaceous insertion compound as claimed in claim 10 wherein themethylene blue absorption capacity of the carbonaceous host is less thanabout 4 micromoles per gram of host;
 13. A carbonaceous insertioncompound as claimed in claim 10 wherein the surface area of thecarbonaceous host as determined by BET is less than about 300 m²/gram.14. A carbonaceous insertion compound as claimed in claim 10 wherein thealkali metal is lithium.
 15. A carbonaceous insertion compound asclaimed in claim 14 wherein the pre-graphitic carbonaceous host has areversible capacity for lithium insertion, an irreversible capacity forlithium insertion, and a surface area accessible to a non-aqueouselectrolyte.
 16. A carbonaceous insertion compound as claimed in claim15 wherein the accessible surface area is sufficiently small such thatthe irreversible capacity is less than about a half that of thereversible capacity.
 17. A carbonaceous insertion compound as claimed inclaim 10 wherein the pre-graphitic carbonaceous host is prepared bypyrolyzing an epoxy precursor comprising an epoxy novolac resin.
 18. Acarbonaceous insertion compound as claimed in claim 17 wherein the epoxyprecursor comprises a hardener in a range from zero to about 40% byweight.
 19. A carbonaceous insertion compound as claimed in claim 18wherein the hardener is phthallic anhydride.
 21. A carbonaceousinsertion compound as claimed in claim 19 wherein the epoxy precursor iscured at about 120° C. before pyrolysis.
 22. A carbonaceous insertioncompound as claimed in claim 17 wherein the pyrolysis temperature isattained by ramping at from about 1° C./min to about 20° C./min.
 23. Acarbonaceous insertion compound as claimed in claim 10 wherein thepre-graphitic carbonaceous host is prepared by pyrolyzing an epoxyprecursor comprising a bisphenol A epoxy resin.
 24. A carbonaceousinsertion compound as claimed in claim 23 wherein the pyrolysistemperature is attained by ramping at about 30° C./min.
 25. Acarbonaceous insertion compound as claimed in claim 10 wherein thepre-graphitic carbonaceous host is prepared by pyrolyzing a phenolicresin precursor at a temperature above 800° C.
 26. A carbonaceousinsertion compound as claimed in claim 25 wherein R is less than about1.6.
 27. A carbonaceous insertion compound as claimed in claim 25wherein the phenolic resin precursor is cured at about 150° C. beforepyrolysis.
 28. A carbonaceous insertion compound as claimed in claim 25wherein the pyrolysis temperature is maintained for about an hour.
 29. Acarbonaceous insertion compound as claimed in claim 25 wherein thephenolic resin precursor is of the novolac type.
 30. A carbonaceousinsertion compound as claimed in claim 25 wherein the phenolic resinprecursor is of the resole type.
 31. A carbonaceous insertion compoundas claimed in claim 30 wherein the phenolic resin precursor is pyrolyzedat a temperature in the range from about 900° C. to about 1100° C.
 32. Acarbonaceous insertion compound as claimed in claim 10 wherein thepre-graphitic carbonaceous host is prepared by pyrolyzing a carbohydrateor carbohydrate containing precursor at a temperature above 800° C. 33.A carbonaceous insertion compound as claimed in claim 32 wherein the tapdensity of the carbonaceous host is greater than about 0.7 g/ml.
 34. Acarbonaceous insertion compound as claimed in claim 32 wherein R is lessthan about
 2. 35. A carbonaceous insertion compound as claimed in claim32 wherein the carbohydrate precursor is pyrolyzed at a temperature inthe range from about 900° C. to about 1100° C.
 36. A carbonaceousinsertion compound as claimed in claim 35 wherein the pyrolysistemperature is maintained for about an hour.
 37. A carbonaceousinsertion compound as claimed in claim 35 wherein the pyrolysistemperature is attained by ramping at a rate of about 25° C. per minute.38. A carbonaceous insertion compound as claimed in claim 32 wherein thecarbohydrate precursor is a sugar.
 39. A carbonaceous insertion compoundas claimed in claim 38 wherein the sugar is sucrose.
 40. A carbonaceousinsertion compound as claimed in claim 32 wherein the carbohydrateprecursor is a starch.
 41. A carbonaceous insertion compound as claimedin claim 32 wherein the carbohydrate precursor is a cellulose.
 42. Acarbonaceous insertion compound as claimed in claim 41 wherein thecellulose is selected from the cellulose containing group consisting ofred oak, maple, walnut shell, filbert shell, almond shell, cotton orstraw.
 43. A carbonaceous insertion compound comprising: a pre-graphiticcarbonaceous host prepared by pyrolyzing an epoxy novolac resin havingthe formula

at a temperature above about 700° C. and below about 1100° C.; andlithium atoms inserted into the carbonaceous host.
 44. A carbonaceousinsertion compound comprising: a pre-graphitic carbonaceous hostprepared by pyrolyzing a bisphenol A epoxy resin having the formula

at a temperature about 800° C., and lithium atoms inserted into thecarbonaceous host.
 45. A process for preparing a pre-graphiticcarbonaceous host for a carbonaceous insertion compound comprisingpyrolyzing an epoxy precursor at a temperature above 700° C. or aphenolic resin precursor at a temperature above 800° C., or acarbohydrate precursor or a carbohydrate containing precursor at atemperature above 800° C., such that the empirical parameter R,determined from an x-ray diffraction pattern and defined as the {002}peak height divided by the background level, is less than about 2.2. 46.A process for preparing a pre-graphitic carbonaceous host for acarbonaceous insertion compound comprising pyrolyzing an epoxy precursorat a temperature above 700° C. such that the empirical parameter R,determined from an x-ray diffraction pattern and defined as the {002}peak height divided by the background level, is less than about 2.2. 47.A process as claimed in claim 46 wherein the epoxy precursor is an epoxynovolac resin with formula

and the pyrolysis is performed at a maximum temperature below about1100° C.
 48. A process as claimed in claim 46 wherein the epoxyprecursor is a bisphenol A epoxy resin with formula

and the pyrolysis is performed at a temperature about 800° C.
 49. Aprocess for preparing a pre-graphitic carbonaceous host for acarbonaceous insertion compound comprising pyrolyzing a phenolic resinprecursor at a temperature above 800° C. such that the empiricalparameter R, determined from an x-ray diffraction pattern and defined asthe {002} peak height divided by the background level, is less thanabout 2.2.
 50. A process as claimed in claim 49 wherein the phenolicresin precursor is of the novolac type.
 51. A process as claimed inclaim 49 wherein the phenolic resin precursor is of the resole type. 52.A process as claimed in claim 51 wherein the pyrolysis is performed at atemperature in the range from about 900° C. to about 1100° C.
 53. Aprocess for preparing a pre-graphitic carbonaceous host for acarbonaceous insertion compound comprising pyrolyzing a carbohydrateprecursor or a carbohydrate containing precursor at a temperature above800° C. such that the empirical parameter R, determined from an x-raydiffraction pattern and defined as the {002} peak height divided by thebackground level, is less than about 2.2.
 54. A process as claimed inclaim 53 wherein the carbohydrate precursor is selected from the groupconsisting of sugar, starch, and cellulose.
 55. A process as claimed inclaim 53 additionally comprising precarbonizing the carbohydrate bywashing with an acid.
 56. A process as claimed in claim 55 wherein thecarbohydrate is sucrose.
 57. A process as claimed in claim 55 whereinthe acid is concentrated sulfuric acid.
 58. An electrochemical devicecomprising an electrode wherein a portion of the electrode comprises thecarbonaceous insertion compound as claimed in claim 1, 2, 10, 17, 23,25, or
 32. 59. A battery comprising an electrode wherein a portion ofthe electrode comprises the carbonaceous insertion compound as claimedin claim 1, 2, 10, 17, 23, 25, or
 32. 60. A non-aqueous batterycomprising: a cathode comprising a lithium insertion compound; anon-aqueous electrolyte comprising a lithium salt dissolved in a mixtureof non-aqueous solvents; and an anode comprising the carbonaceousinsertion compound as claimed in claim 1, 10, 17, 23, 25, or 32 whereinthe alkali metal is Li.
 61. The use of a carbonaceous insertion compoundin an electrode of an electrochemical device, said carbonaceousinsertion compound comprising: a pre-graphitic carbonaceous hostprepared by pyrolyzing an epoxy precursor at a temperature above 700°C., or a phenolic resin precursor at a temperature above 800° C., or acarbohydrate precursor, or a carbohydrate containing precursor, at atemperature above 800° C., wherein the empirical parameter R, determinedfrom an x-ray diffraction pattern and defined as the {002} peak heightdivided by the background level, is less than about 2.2; and atoms of analkali metal inserted into the carbonaceous host.
 62. The use of acarbonaceous insertion compound in an electrode of an electrochemicaldevice, said carbonaceous insertion compound comprising: a pre-graphiticcarbonaceous host prepared by pyrolyzing an epoxy precursor at atemperature above 700° C. wherein the empirical parameter R, determinedfrom an x-ray diffraction pattern and defined as the {002} peak heightdivided by the background level, is less than about 2.2; and atoms of analkali metal inserted into the carbonaceous host.
 63. The use of thecarbonaceous insertion compound as claimed in claim 62 wherein the epoxyprecursor is a novolac epoxy resin.
 64. The use of the carbonaceousinsertion compound as claimed in claim 62 wherein the epoxy precursor isa bisphenol A epoxy resin.
 65. The use of a carbonaceous insertioncompound in an electrode of an electrochemical device, said carbonaceousinsertion compound comprising: a pre-graphitic carbonaceous hostprepared by pyrolyzing a phenolic resin precursor at a temperature above800° C. wherein the empirical parameter R, determined from an x-raydiffraction pattern and defined as the {002} peak height divided by thebackground level, is less than about 2.2; and atoms of an alkali metalinserted into the carbonaceous host.
 66. The use of the carbonaceousinsertion compound as claimed in claim 65 wherein the phenolic resinprecursor is of the novolac type.
 67. The use of the carbonaceousinsertion compound as claimed in claim 65 wherein the phenolic resinprecursor is of the resole type.
 68. The use of a carbonaceous insertioncompound in an electrode of an electrochemical device, said carbonaceousinsertion compound comprising: a pre-graphitic carbonaceous hostprepared by pyrolyzing a carbohydrate precursor, or a carbohydratecontaining precursor, at a temperature above 800° C. wherein theempirical parameter R, determined from an x-ray diffraction pattern anddefined as the {002} peak height divided by the background level, isless than about 2.2; and atoms of an alkali metal inserted into thecarbonaceous host.
 69. The use of the carbonaceous insertion compound asclaimed in claim 68 wherein the carbohydrate precusor is selected fromthe group consisting of sugar, starch, and cellulose.
 70. The use of thecarbonaceous insertion compound as claimed in claim 62, 65 or 68 whereinthe alkli metal is lithium and the electrochemical device is anon-aqueous battery, the battery comprising a cathode comprising alithium insertion compound; a non-aqueous battery electrolyte comprisinga lithium salt dissolved in a mixture of non-aqueous solvents; and ananode comprising said carbonaceous insertion compound.